10-40 or 20-50 oil ???

[DWRAT]

What do you AZ guys think?
My cars has been using 20-50 oil for at least the last 5 years that I know of.
My pressure is a bit high when cold (65-70) but once warm I get about 40 psi on idle and 60 psi over idle.

I have read a lot about not using 20-50 but maybe those guys are in Mikiec country.

[mikiec]

Here is some information.

Motor Oil Viscosity Grades Explained in Layman's Terms

[cycleguy55]

Read all 12 sections of this (Motor Oil 101 - Bob is the Oil Guy - Bob is the Oil Guy) and you'll probably never use 20W50 again.

[RICK LAKE]

DWRAT DW with out the clearances on the bottom end and what type of oil you are using I would be very careful. The numbers you tell are fine. Why the change? If you want to poke the bear with a stick,,.
I run a 15-40 rotella. I have an HVHP oil pump that when started is 125-128 psi. I let the motor warn up like you should. When Hot, I have a 35-40 psi at idle 750rpms, and 75-80 hot over 2,000 rpms. This is hard on the distributor gear if clearance is not setup right and camshaft has too much end play. Also have added oil to the 2 gears at the contact point. My car does 98% racing. I use 10-30w for breakin of the first 20 minutes at 2,000 rpms. After this, new filter and straight to 15-40. I also add 1 quart of lucas oil suppliment when the oil is hot. This helps prevent dry startups. I have also added an accusump as a preoiler before starting the motor. I get 35 psi on the gauge, wait 10 seconds and crank.
There are some good oils out there, Couple of guys like the Joe Gibbs customs. Very are not cheap but looking at repair of a $15-30K motor in value is a no brainer.
I like the 15-40 and run this only. Same block, went from a 452 to a 484 and still have no wear and same clearances to the .0000" diget. Save the high pressure numbers for another day and amount of abuse.
You have to see what the motor likes. Watch the oil pressures. IMO no FE motor should idle with less than 30 psi and be safe. Have to remember that the oil pressure reading is in the beginning of the oil supply and not at the back rods of #4 and #8. A test was done that showed a 10-20psi drop in pressure. Depends on the clearances. I have seen motor damage and it seens to be the back rods and mains that recieve the most spun bearings and damage in a block.
Go down one weight and test the motor. Warmup is important. Good luck. Rick L.

[Gaz64]

Originally Posted by DWRAT

What do you AZ guys think?
My cars has been using 20-50 oil for at least the last 5 years that I know of.
My pressure is a bit high when cold (65-70) but once warm I get about 40 psi on idle and 60 psi over idle.

I have read a lot about not using 20-50 but maybe those guys are in Mikiec country.

One of my cars runs about 50 psi and still spins reliably to 6800 if I want to.

It idles at 20 psi.

I run a 5w40.

It used to have more oil pressure with the thicker oil I ran 25-30 at idle, 60 at 3000, but it made less power.

[JBCOBRA]

My car seems to love the 15/50 Hot Rod oil from Gibbs. On my 4th year using it.
Cold oil pressure is 65-70 at 2000rpm
220 degree oil is 50 at 2000rpm. 20-25 at idle
Seems ideal to me

[Bob Broberg SPF667 460BB]

Dan, everyone is going to have a favorite viscosity. If you are not racing, you probably don't need the 50 weight when hot and most new cars with high hp have narrower clearances in their engines so 5 or 10 weight when cold is preferred. Since most cobra owners change their oil often you also probably don't need synthetic. I have 62K+ miles on my motor and I simply use name brand whatever is on sale with ranges of 5-20 to 10-40 (if racing) but mostly 30w or 10-30. Don't "play" until oil temp is off the pin and check it every time before you use it. I add an oil treatment with Zinc, like STP the first time my level is down 1/2 quart.
My motor was setup one the "loose" side for endurance and still has good compression but uses some oil when I play too much at high rpm. Which is rare now.

AZ Bob

[Bernica]

Originally Posted by Bob Broberg SPF667 460BB

Dan, everyone is going to have a favorite viscosity. If you are not racing, you probably don't need the 50 weight when hot and most new cars with high hp have narrower clearances in their engines so 5 or 10 weight when cold is preferred. Since most cobra owners change their oil often you also probably don't need synthetic. I have 62K+ miles on my motor and I simply use name brand whatever is on sale with ranges of 5-20 to 10-40 (if racing) but mostly 30w or 10-30. Don't "play" until oil temp is off the pin and check it every time before you use it. I add an oil treatment with Zinc, like STP the first time my level is down 1/2 quart.
My motor was setup one the "loose" side for endurance and still has good compression but uses some oil when I play too much at high rpm. Which is rare now.

AZ Bob

My clearances are as follows and I am running Joe Gibbs XP3. It's already got the zinc in it. Pressure starts high and settles at around 50-60 after warm up. Fluctuates but never below 40, which is my worry point.

Mains: .0022-.0025
Piston to wall: .004
Rods: .0025-.0030

[1985 CCX]

High Zinc content #1;
second typically 5-40 for me

[Bernica]

Originally Posted by 1985 CCX

High Zinc content #1;
second typically 5-40 for me

So, the XP3 I am running equates to 10-30. With my clearances, does that sound right?
See? Now you have me second guessing myself!

[madmaxx]

Anything above 60 psig is a waste and depending on where the oil pump RV is set in the oil pump may be just dumping back to the pan creating heat.

I suggest 10W30 if you can get 55-60 psig at 6K rpm. Long story but I had a stroked 351W that had 42 psig at 6K rpm and never did a lick of damage to anything.

For each jump in viscosity at 100C you gain 5psig oil pressure, so 10W30 vs 10W40 is 5 psig than another 5 psig going to 20W50. I ran the living sheet out of my engines and ran 10W40 and had perfect oil pressure. I also noted the higher viscosity oil like the 20W50 the oil temp ran about 8C hotter. It was always at 100C where 10W30 was at 85C and 10W40 was at 90C water temp at 88C

[philminotti]

I run the Joe Gibbs 15-50 in my 482 FE. Now that it's fully broken in, my 200 degree oil temp pressure at 2K is 55 and 20-25 at idle. I idle it down at 900, so I could probably have 30-35 at 1000, but I like the sound at 900. My cold idle pressure is 70.

[1985 CCX]

Don't second guess. Sounds right.
I have a solid lifter 289.
Important that it's not overdone is all.
Zinc = lubricant to soften blow
Flow is 5 or 10-40 part.
20-50 builds pressure etc that may not benefit motor.

[DWRAT]

Thanks everyone for your thoughts.
I just ordered some Brad Penn 10w-40 and hopefully it works well.

[xb-60]

I've used 20W-50 Valvoline in my Alfa twin cam for the last 39 years. The original engine was sidelined at around 220,000km, but only because of a significant rear main seal leak. Apart from leaks, the original engine and its replacement did not / do not appear to use any oil that is measureable.

Digressing from the original question just for a minute....if most wear occurs at startup, why do modern ECU controlled engines zing up to close to 2000rpm immediately? Seems counterproductive to me, probably something to do with less emissions, but surely causes more wear.

Cheers,
Glen

[RET_COP]

I'll second MadMaxx from my own experiences. More flow=cooler bearings, quicker lubrication and faster to take up bearing clearances. considering psi. of course.

[Bernica]

Originally Posted by DWRAT

Thanks everyone for your thoughts.
I just ordered some Brad Penn 10w-40 and hopefully it works well.

Seems like Brad Penn and Gibbs are the choices for a lot of folks, while I have several friends that swear by Rotella which I only knew growing up was for tractors.

[Karl Bebout]

Tractor-Truck Engine--

Just like the Chevy RAT engines, weren't Ford big blocks developed for trucks? Rotella should be just fine.

[madmaxx]

BraddPenn is great but can be pain to find sometimes. I always used Mobil 1 10W40 and a 1/4 bottle of redline break-in additive to get the EP additives up. In the end I am sure it was useless but the bottle was $12.00. With hydraulic roller engines the additives are not "needed". My engines had 450lbs open valve spring pressure and 170lbs close so I theorized the rocker arm pintles could use the additive. I always had stock ford racing lifters, and never had a problem.

[DWRAT]

I just change my oil with Brad Penn 10w-40 and I still have 65 psi on cold start.
Didn't have a chance to warm it up yet.
Planning on taking up to Flagstaff for the summer.