Ha ha. I didn't expect anyone to say they based their statements on outmoded thinking.....

Z

Z,

I have seen things on a much larger sample scale than 99% of the people here. I also get to talk to a lot of engine builder friends who again see things on a very large sample scale. From my standpoint experience trumps everything else.

Brent,

I am behind you 100%. Discussing the relative utility of one oil or another when your N=1 or 2 does not provide significant numbers to make generalizations to others. However, when your N encompasses many builds and input from other builders you have a greater understanding of the range of possible effects.

In addition, as you have said, each build is slightly different and the oil needs are different based upon each build.

Thanks for the clarification Dan [post #16]. I believe your engine likes the heavier oil also. Like I said, it's engine specific and what you are doing with that engine.

Brent,

Zinc is needed in oils primarily as lubrication for flat tappet cams. Does the extra zinc offer any benefits in roller engines?

John

Gents,

I am not critiquing anyone's choice, I was just curios with what others are running. I like the higher pressure and it can get hot and muggy here in Columbus in the summer.
The Rotella Synthetic works well and I never hear lifter noise. I do have small leaks around the valve cover and rear intake seal. No crank seal leaks. I know that from having the flywheel ring gear replaced last year.

Would it be accurate to state at running higher pressures you would have greater leaks? It seams like a double edged sword. If you run a lighter oil it would thin out when warmer. That would seem to make it more prone to leaking. If a heavier oil is used, it seems that pressures would be higher. Is it just me or wouldn't you want something in the middle? Not trying to start a conflict here. As a novice on this subject, I just trying to think if its worth trying something different.

Phil

I certainly respect you experience, and what it has taught you. I only have 45 years of experience in engine building, maybe not much by your standards. But enough so that i am confident in drawing a few conclusions from what I have seen others do, and what I have personally done.

I am not currently building engines professionally. After doing so since 1966, I have retired (2011). My main professional experience has been in the 2 wheel world, but I certainly have plenty of time building auto engines as well

I didn't start using Mobil 1 products until the mid 1980's. Before then I would routinely use Castrol 20w-50 in all British engines I built, including competition Triumph TR2, TR3, TR4, and Spitfire's. As well as the Jag 3.8 & 4.2 engines. I also built numerous FE and SBF engines starting when I was 13 in my uncles shop, several of them were for NASCAR type cars competing on the outlaw tracks (not sanctioned). I couldn't tell you the exact date, but in any case by the 1990's I was using synthetic oil in every engine i built, the ones referenced above, as well as Datusn 240z, all Engiish motorcycles, primarily BSA, Triumph, and Nortons of the 1960's and 1970's and all years of Hondas, Kawasaki's, Ducati, and a few HD's. Along the way I did manage to put Mobil 1 in numerous 428 SCJ and 289 HiPo engines without the sky falling, and without them leaking when they hadn't been leaking before. The ones that were leaking to begin with, still leaked, but no more than before the switch.

As you can see, my experience, although only four and half decades, has shown me a different set of conclusions than your experience has shown you. Nothing wrong with that that I can see. I do note that I am not the only person to report using a synthetic oil in vintage Ford engines, and liking it. My overriding reason for using synthetic oil is to benefit from the reduced friction vs. conventional oil, a quality that has been demonstrated by others far more knowledgable than me.

Z.

Phil,

I had asked that question of my mechanic last year, wondering if running a heavier oil at higher pressures could lead to gasket failure and his take was that our engines do not produce enough pressure to blow a gasket out that was properly sealed. He runs 1200 hp in his drag race car and has not had an issue with too much oil pressure. I imagine there are downsides, as everything tends to be double edged.

Run what works in you engine and only consider a change if problems start.

Well, there should be no gasket in an engine that's in front of oil pressure. Every gasket and seal should only be exposed to splash and fluid level only.

Yes to gasket failures from high weight oil
 

Guys there are a couple different types of oil leaks
Lets start with the rearmain seal on an FE motor. If it's a rope seal, they are designed to seep or leak at the crankshaft. This helps keep the rope from drying out and from heat and really leaking. Most of the builders here now have a 2 piece Rubber/Plastic seal for the crankshaft. Most FE's don't mark their ground any more. Installing the seal in a clean and correct way and allowing the RTV 24 hours to cure, with the rotation of the seal being 10 to 20 degrees off the flat of the block should product no leak. Rope seal will seep over time.
Blowing out a gasket, I have done this on a gm product but not on an FE motor, if you call an Shelby block a true FE motor. This was from running a 10-40 oil. I have had cork gaskets break out over time. Had an oil fire at the last R&G. No damage just the oil hitting the headers. I run a PCV valve and breathers on the motor and have little pressure inside the motor. It just cracked out from age. Mechanic got cheap and reused 1 too many times.
If you blow out a gasket in a low pressure area, your motor is failing or your pcv or valve cover breathers are not working. Some guys are running vacuum pump systems the will not allow pressure to build up in a motor. Dry sump systems work the same way with less vacuum building up in the motor. A gasket that is weak to seal could get sucked in.
Bottom line is proper assembly, clean area, and I use HI-tac on all my motors and the basic cheap old Fel-pro master gasket set. The gray RTV for all sealing corners. Last note is warning up a motor before driving it on the street or track hard. If I took out my motor with running about 130 psi oil pressure it could do some damage, blow a gasket, or break the oil pump drive or distibutor gear.
I run rolleta 15-40. I do get a leak at the rear main seal because I run 1.5 quarts over fill and it leaks out when the motor is not running. level drops with motor turning and leak stops. I go a season before changing oil. My whole system with lines, accusump, oil pan hold just under 13 quarts. Run a Fram oil filter. That's it. Rick L.

If I'm understanding this correctly, bearing clearances dictate the weight of oil you should run. But what if you don't know what those clearances are? Joe Lapine built the motor in my Cobra. I'll give him a call sometime to see what he recommends, but what if you don't know the builder? Is there a certain pressure hot and cold that will be a tell tale sign?