The Stovebolt Site Forums The Shop Area Engine Shop Synthetic oil ??

I'm in the prosses of doing an oil change on my recently rebuilt 261 . I have about 4,000 miles since rebuild and have been using Shell Rotella T 15 w 40 oil till now .
I can't seem to find the same none synthetic oil for some reason , will using the same grade in synthetic be advisable ???
Thanks in advance for any input .

John

I will give you my 2 cents on this issue for what its worth. The motor was engineered with bearing clearances and oil passage clearances, and yes, leak clearances re the oil pump and gaskets, that were based on dino oil. Synthetics are really excellent and hence, modern engines are designed for their use. The modern designs take into account all of the terrific characteristics that make synthetic oils so good at what they do. Now, using a full synthetic in an old 261, even a recently rebuilt 261 to me is just asking for trouble from leaks to bearing cushion.

I know a lot of guys love the Rotella. But that lubricant no longer has the zinc and phosphorus package that our old motors need so I am not totally sold on still using the current formulation of that stuff.

On the other hand, there are a couple of companies selling dino based oil that has sufficient amounts of zinc and phosphorus. I prefer Penn Grade 1 which is Pennsylvania oil (its actually the old Kendal 1 oil) with a synthetic additive package and zinc and phosphorous. I am particularly hard on my motors, and one of my 261 motors sees as much as 5500-6000 rpms without issue. Other companies sell something similar so you might consider skipping a full synthetic oil and use oil that is primarily dino based with the necessary additive packages to keep the motor lubricated, the bearings properly cushioned and the cam and lifters happy happy happy.

Considering the weather where you are, IMHO I would use something a bit lighter like 10W30.
You'll be surprised at how your cranking speed goes up, and the delay for your oil light to go out with a lighter pre-W number.

Use Walmart 15W40. It's made to the same spec as Rotella at less than half the price. I use it in my 38 and 53.

I use 15W40 Delo in my dino engines, still has the zinc additive.

ALL of the diesel rated oils, including DELO 400 have reduced the zinc and phosphorus additive by about 25%. Anything with a CK-4 rating will have reduced ZDDP. I have used DELO 400 in my diesel for years and the attached oil analyses shows when they reduced the additive package. If you can find CJ-4 rated oil (good luck), that has the higher ZDDP additive. Seems like all diesel rated oils have been scarce lately, no matter what the rating.
But using a diesel rated oil in a gas engine is still a good thing, as the additive package is higher than a straight gas rated oil.

Thank you one and all for the replies , they were informative .

John

1 winter 100 years ago, I had to change the oil in a VW beetle, and all we had was straight 30. It didn't crank slowly: even with a jumper to add a 2nd battery the starter didn't turn the flywheel at all. We had to tow the car to start it. Gene Berg said more Type I engines blew up from using heavy oil than any other detectable cause.

At cruising speed, heavier oil has already opened the relief valve, so the local pressure at the journal face has not improved.
My joke: in a multigrade oil, the number before the "W" is the time in seconds for oil pressure to reach the farthest bearing, tappet, rocker arm.
20W50: 20 seconds
5W40 (which I use in my 2JZ engine): 5 seconds