Question on oil temperature

[YerDugliness]

I've been wondering about condensate contamination recently on my (I think) box-stock 5.0 HO engine in my Cobra. I notice that on cool days the coolant temperature stays around 160* unless I turn off the puller fan on the radiator (it is a large Griffin radiator....at least it never overheats). If that is so, then the oil temperature must be even lower, as I seldom drive it anywhere near the upper RPM limits in town.

I'm just curious...what temp thermostats does everyone use? I have no idea what mine is, but think I'll swap it out for a 195* unit for the winter, then back to a 180* unit for the summer.

I guess I need an oil temp gauge more than I need the non-functional amp gauge (I have no oil cooler). Would it be best to connect the oil temperature gauge at the rear of the block, right in front of the firewall?

TIA for whatever advice y'all might have. I've seen engines all sludged up inside from failure to run a thermostat, but never gave much thought to the fact that failure to boil off the condensate in the oil might do the same thing.

Cheers!

Dugly

[DAVID GAGNARD]

Originally Posted by YerDugliness

I've been wondering about condensate contamination recently on my (I think) box-stock 5.0 HO engine in my Cobra. I notice that on cool days the coolant temperature stays around 160* unless I turn off the puller fan on the radiator (it is a large Griffin radiator....at least it never overheats). If that is so, then the oil temperature must be even lower, as I seldom drive it anywhere near the upper RPM limits in town.

I'm just curious...what temp thermostats does everyone use? I have no idea what mine is, but think I'll swap it out for a 195* unit for the winter, then back to a 180* unit for the summer.

I guess I need an oil temp gauge more than I need the non-functional amp gauge (I have no oil cooler). Would it be best to connect the oil temperature gauge at the rear of the block, right in front of the firewall?

TIA for whatever advice y'all might have. I've seen engines all sludged up inside from failure to run a thermostat, but never gave much thought to the fact that failure to boil off the condensate in the oil might do the same thing.

Cheers!

Dugly

I'm not 100% sure, but I think the 5.0 HO engines came with 190 or 195 degree thermostats. Depending if it's still EFI or carbed,(I see your engine is carbed, so 180 degree thermostat would be correct for it) I would use that or a 180 thermostat, nothing lower. Soounds like you have a very efficeint cooling system on your car, you might try blocking off a few inches of the bottom of your radiator with the wide clear packing tape to help keep the water temp in the 180 to 190 range...
I use the same 180 degree thermostat on my street car and race car!!!!!

Water temp has little to no bearing on your oil temp.,oil temp is determined by rpms and bearing clearance mostly and oil viscosity to some degree....not sure I understand what you mean by putting your oil temp gauge at the rear of the block, it needs to be low in the oil pan where it will stay submerged in oil to get any kind of accurate reading...
Idealy,to me anyway, water temp should stay bewteen 180 and 190, and oil temp from 190 to 220....

David

[bobcowan]

- Water will evaporate from an emulsion at low temps - like 100*; it just takes a long time. Frequent short trips cause the sludge to develop because it gets warm for a very short period of time. Longer trips get the oil and water to higher temps, and for longer periods, that's why the sludge usually resolves. The end result is correct, but the cause- effect assumption is slightly off.

If you could run the engine for an hour at 100*, the same thing would happen. But, why would you do that? That would be a bad thing to do for a lot of reasons.

- A good spot for the oil temp sender depends on your engine set up. With an external cooler, I like to know what the temp is as it's going in to the engine. With no external components, the side of the pan is a good spot. With the proper adapter, you can put it where the factory level sensor used to be.

- A stock Mustang usually has a 195* thermostat. The higher operating temp improves emissions. The computer is programmed to look for that temp before switching to closed loop, and then it gets off the cold enrichment map. You can use a 160* or 180* thermostat if you reprogram the computer to see that as normal operating temp. Of course, if you've dumped the computer altogether and gone with a carb, you can use anything you want, and adjust the choke accordingly.

Lots of studies on cold weather operation show increased cylinder wall wear at temps <160* or so.

The thermostat only sets rough minimum temps.

- Water is a small by product of combustion. Because of the heat involved, you know the water is well vaporized. But, the condensation in every other part of the engine is not the same thing. On a good engine, the blow by will be 10% or less. If you're getting that much water simply from blow by, you have other issues to address.

- oil sludge is more of a problem in some engines than it is in others; the 2001-2004 Dodge Dakota 4.7l comes to mind. It was a problem even for people who made frequent long drives - 20 to 40 mile commutes. So, obviously engine design has a something to do with it. That engine even had a recall (or maybe a TSB?) on that particular concern. IIRC, the fix was something simple like a new PVC hose routing.

[jhv48]

Apples to oranges once again.

Engines are designed to be operated within a certain temperature range. If you fail to meet that requirement, condensation will occur and will not be boiled off. Duh! That's why manufacturers recommend more frequent oil changes for low mileage vehicles.

But, i am talking about normally operated vehicles. Ones that reach normal operating temps. If you notice brown muck in the oil of one of these vehicles, then you probably have a serious water leak.

[YerDugliness]

Originally Posted by DAVID GAGNARD

I'm not 100% sure, but I think the 5.0 HO engines came with 190 or 195 degree thermostats. Depending if it's still EFI or carbed,(I see your engine is carbed, so 180 degree thermostat would be correct for it) I would use that or a 180 thermostat, nothing lower.

....not sure I understand what you mean by putting your oil temp gauge at the rear of the block, it needs to be low in the oil pan where it will stay submerged in oil to get any kind of accurate reading...

Idealy,to me anyway, water temp should stay bewteen 180 and 190, and oil temp from 190 to 220....

David

Thanks, David, for the advice...I'll definitely change out the thermostat while I have the valve covers off for gasket replacement!

As for my comment regarding the "oil temp gauge at the rear of the block", I guess the keyboard gremlins got me that time. I was trying to say "..sensor location for the oil temp gauge"...the rear of the block seemed to be the best idea as I thought there was a place to tap into the oiling system for a pressure gauge...I see now that those "ports" are coolant and vacuum "ports". I do have a Fox body oil pan on the Cobra right now, and there is a plugged port on the driver's side of the pan, directly to the side of the rear oil pan drain plug, that was probably for a factory "low oil" sensor, I'll try to use that location.

I am guilty of thinking that I need heavy viscosity oil in my pan...think I will switch to 15W-30 or 15W-40. Right now there is a very slight leak at the rear corner of the passenger's side valve cover, so I check the oil level every time I get in my car. It must be a very slight leak, I guess, as the oil level never seems to drop on the dipstick. My oil pressure VERY seldom drops to 40PSI, and usually at any RPM level above idle is at 60PSI (VDO gauges, no idea how accurate they are).

Cheers, and thanks, again! An oil temp gauge is definitely in my Cobra's future.

Dugly

[mattpatt]

Talking about pressure - when I'm around a temperature of ~90-95 C (standard Superformace sensor at remote filter) I have ~ 40-50 psi. At ~105 C it drops to ~20-25 psi. I'm using Joe Gibbs HR-2 (30 weight). Are these lower pressures OK or should I up the weight?

thx

[Jerry Clayton]

Do you have the cooler hooked up or is it just a dummy with lines tucked up into fenders?

[bobcowan]

Originally Posted by YerDugliness

I do have a Fox body oil pan on the Cobra right now, and there is a plugged port on the driver's side of the pan, directly to the side of the rear oil pan drain plug, that was probably for a factory "low oil" sensor, I'll try to use that location.

Mike Forte makes an adapter especially for this application.

I am guilty of thinking that I need heavy viscosity oil in my pan...think I will switch to 15W-30 or 15W-40. Right now there is a very slight leak at the rear corner of the passenger's side valve cover, so I check the oil level every time I get in my car. It must be a very slight leak, I guess, as the oil level never seems to drop on the dipstick. My oil pressure VERY seldom drops to 40PSI, and usually at any RPM level above idle is at 60PSI (VDO gauges, no idea how accurate they are).

Cheers, and thanks, again! An oil temp gauge is definitely in my Cobra's future.

Dugly

Good operating oil pressure should around 45psi or so. It will drop a bit at idle, but not too much. Too much oil pressure is not necessarily a good thing. The oil should be "thick" enough to maintain proper oil pressure. Whatever viscosity that might be. In the winter, you should run a fairly low winter weight. Since we rarely drive our cars in sub-zero temps, a 15W is probably fine.

I use 5W-30 true syntheitc year 'round. Maintaining proper oil pressure isn't a problem. When hot and on the track, it runs about 45-50psi. I tear the engine down every two years. The bearings look excellent after two years of abuse. I replace the bearings (just because) but I'v never had to cut the crank. Obviusly, crank and bearing wear is not an issue.

Originally Posted by mattpatt

Talking about pressure - when I'm around a temperature of ~90-95 C (standard Superformace sensor at remote filter) I have ~ 40-50 psi. At ~105 C it drops to ~20-25 psi. I'm using Joe Gibbs HR-2 (30 weight). Are these lower pressures OK or should I up the weight?

thx

20-25psi at hot idle is fine; while running down the highway it's probably a little bit low. I would investigate that a bit more closely.

[YerDugliness]

Thanks for the tip on the Mike Forte oil pan adaptor, Bob! I had figured I'd have to cobble up a bunch of brass adaptors, it's good to know that someone else has taken all the guess work out of it for me.

Originally Posted by bobcowan

Good operating oil pressure should around 45psi or so. It will drop a bit at idle, but not too much. Too much oil pressure is not necessarily a good thing. The oil should be "thick" enough to maintain proper oil pressure. Whatever viscosity that might be. In the winter, you should run a fairly low winter weight. Since we rarely drive our cars in sub-zero temps, a 15W is probably fine.

I use 5W-30 true syntheitc year 'round. Maintaining proper oil pressure isn't a problem. When hot and on the track, it runs about 45-50psi. I tear the engine down every two years. The bearings look excellent after two years of abuse. I replace the bearings (just because) but I'v never had to cut the crank. Obviusly, crank and bearing wear is not an issue.

I suspect my engine has a high-pressure oil pump and that it is already at the limits of the relief spring once I get the RPM's above an idle. I would rather use a high-volume pump, but for now it has what it has, so I'll deal with that until it is time to tear it down. At this point the only place where I have any oil leaks is the valve cover, so I know the pressure is not adequate to force oil past the front/rear seals, etc. It is totally street driven, and rather tamely for the most part as I know the local police would love to nail me for anything they can....I was on my way to a car show in Beaumont, TX and was stopped by a DPS officer for having an expired registration. It took 2 minutes to show him my receipt from the new registration the day before, but it took an hour to get away from him after that, he was a "car guy" too and wanted to talk cars.

As for the synthetic oil, I've been a bit reluctant to use it since I put it into a new Mitsubishi Eclipse I bought for my daughter (after 12,000 miles with normal petroleum based oil) and the car developed a severe oil consumption problem. I know it would be better from the standpoint of heat tolerance, and probably from the standpoint of wear protection, but that little experience I had with the synthetic oils has me afraid to try again.

Once I get the valve-cover gaskets and the thermostat replaced, I'll experiment around with oil viscosities to see which meets the guidelines you posted. I don't mind "only" 45 at full pressure, but would want at least 30 at an idle when at operating temperature.

I once had a '66 Cadillac with the 429CID V-8...the pressure required to illuminate the "idiot light" for low oil pressure was 8PSI, no kidding! I mention that b/c I guess it just illustrates how little oil pressure is required to maintain a decent film on the bearings and other operating parts, but I would still like for the low RPM oil pressure to be better than "minimum".

At some point I plan on installing an Oberg oil filter "downstream" from the canister filter...right now I use Purolator's "99%" efficiency oil filter (reportedly designed for the synthetic oils), but I like the idea of the Oberg as a "fail-safe" should the bypass function on the canister filter be triggered, and particularly if I were to install an oil cooler in the scoop below the fishmouth (radiator opening).

Cheers!

Dugly

[bobcowan]

For the engine you have and the way you drive it, there's no need to use a full synthetic oil at $8-9 a qt. Stick with your favorite dino oil and change it once or twice a year. The engine will last a decade, easily.

The Purolater Pure-1 oil filter is one of the best on the market for the money. That's what I use in most everything, and have never had any problems. Adding an additional oil filter isn't necessary.

Of course, a lot of the stuff we do to our cars isn't exactly necessary. Sometimes you just have to do what makes you happy, and helps you sleep at night.

[mattpatt]

Originally Posted by Jerry Clayton

Do you have the cooler hooked up or is it just a dummy with lines tucked up into fenders?

It's the standard SPF MK3 cooler. The oil lines are connected into/out of it.

[Jerry Clayton]

I have serviced SPF where there were dummy lines hooked on the cooler and just tucked up into the fenderwell for looks--the cooler WAS NOT hooked up---sounds like yours might be the same

[bobcowan]

I spent the last couple of days in Estes Park, CO. Friday was a pretty nice day - sunshine, and in the mid 50's until the sun went ebhind the mountains. Then the temps dropped into the mid 40's. Yesterday was considerably colder up there. We went up Trial Ridge Road as far as we could, and then the road was closed due to snow - about 9,500' ASL. We were chased out of town by a snow storm. Once we got down out of the mountains, it was a very nice day again. Sunshine and low 60's.

Because of this conversation, I was wqatching oil and water temps closely, just to see what they would do.

My oil cooler is connected, but it has it's own electric pump, and cools oil in the pan. When the pump is off, there is no oil circulating through the cooler. Absolutly none; so it's like not having a cooler at all. I'm also using a 160* water thermostat. I like to keep the heads as cool as possibly, to limit detonation on hot days.

Water temp was a steady 160*. Driving through stop and go traffic in Denver and Boulder, it got as high as 185*. Oil temp was almost exactly the same. Because oil holds heat longer, it would take a few minutes longer to drop to 160* when we got going again. But then it stayed the same as water temp.

Last Aug, I was in Deadwood, SD, for Kool August Nights. We drove out to Wall one day, and it was about 100*. Driving down the highway at 80mph, water temp was right about 190*. Oil temp was a little higher; then I turned the oil cooler on, and it dropped to about 185*, and the water temp dropped to about 180*.

[madmaxx]

You also like to wear your cylinder walls out. Hot piston, cold cylinder equal wear.

I'm also using a 160* water thermostat. I like to keep the heads as cool as possibly, to limit detonation on hot days.

[DAVID GAGNARD]

Originally Posted by madmaxx

You also like to wear your cylinder walls out. Hot piston, cold cylinder equal wear.

I'm also using a 160* water thermostat. I like to keep the heads as cool as possibly, to limit detonation on hot days.

Yep, your not doing your engine any favors by running water temp of 160........minimum should be 180 on the water and oil temps..........

David

[bobcowan]

Multiple studies show excess cylinder wear occurs at temps under 160*. Engineers generally recommend 160* or more to prevent cylinder wear. There is virtually no differance between 160* and 180*.

And, really, I don't expect to get 120,000 miles out of this engine.

Oil temp is another issue, though. It's generally accepted that minimum operating temp is about 180*+. RP says there is no minimum on their oil m- although I'm not sure I believe that. I can get my temps up to 180-190* on a cold day, but I have to work at it. That's why I use a seperate electric oil pump for the cooler.

[YerDugliness]

Originally Posted by bobcowan

Good operating oil pressure should around 45psi or so. It will drop a bit at idle, but not too much. Too much oil pressure is not necessarily a good thing. The oil should be "thick" enough to maintain proper oil pressure. Whatever viscosity that might be. In the winter, you should run a fairly low winter weight. Since we rarely drive our cars in sub-zero temps, a 15W is probably fine.

20-25psi at hot idle is fine...

I paid particular attention to the coolant temp and oil pressure gauges on a 100+ mile drive yesterday, ambient air temperature about 70*.

Once up to operating temperature (a stable 180* with occasional increases to 190* when I turned off the puller fan), the oil pressure at idle never fell below 30PSI. This drive was in a fairly high-traffic area (I-45 coming into Houston from the north), but it was at a fairly low use time and speeds seldom fell below 60 MPH, most of the time pushing 75-85 MPH. When traveling between 60 and 70 MPH the oil pressure was a steady 55-60 PSI (I think 60 PSI must be the bypass pressure for the oil pump) and the coolant temperature was consistently at 180*. When pushing 80-85 MPH, the pressure fell to about 45-50 PSI when the coolant temperature registered 190* (I had to keep the puller fan off to get it to that range, it never went higher).

Considering the recommendations you made, Bob, it looks like I'm right in the correct pressure range. I would probably run a higher viscosity oil during hotter weather to keep the oil pressure up with the increased coolant temperature that would naturally result from the higher ambient air temperature.

Feeling much better about things now......but, an oil temp gauge is still high on the "Must Have Items" list.

Thanks for the great info!!!

Cheers!

Dugly

[boblyon1]

Matt - just an aside to this thread. I have a 351W stroker in my 633 SPF and learned the hard way that the distributor gear tends to wear if you have a high performance oil pump. I didn't catch it in time and ruined the crank and had to re-build the engine. Good idea to check the distributor gear wear every now and then. My mechanic says the 351W is famous for this problem.

[Mdman352]

I have a 427 (454) S.O. that runs 40-50+ psi oil pressure. I believe my thermostat is a 160. The 4500 CFM fan kicks on at 180F. My oil NEVER gets over 70C and often times barely moves the needle. I run 10-30W regular oil. My oil has never shown signs of milkyness rather just the normal color change as it gets used. I do drive my car "energetically." I have used a temp gun on the oil pan as well as the lines coming from and to the oil cooler and they are in the 130-45F range. My oil temp sensor is on the remote oil cooler adaptor on the block. From reading this thread I am guessing my gauge (Autometer) is not accurate and should be replaced. Any suggestions?
TIA
David A.

[Jerry Clayton]

is your temp sensor reading the oil out of the engine or the oil return to the engine after cooling? if you want to check your guage, put it in boiling water---should read 212 *f