What weight oil are you running

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I ran ROYAL PURPLE 10-40 synthetic on my 340 for 7 years and 20,000 miles when i removed it everything looked new inside . i used zinc additive for the first few oil changes after that I'd add a little zinc every 2 or 3 oil changes . on my stroked 360 a musing valvoline vr1 10-30 synthetic for now . as long as you use a good oil and change it often enough you should be good , and i have never used a quart between oil changes every 5000 miles
 
Great read Wyrm.

Used it on my last summer road trip to the USA in my '72 318 SSP (rebuilt in 1979).

View attachment 1715534089

I have never seen such a super heavy thick oil like that ever before. Wow!

Mattax’s list below about sums it up. Based on bearing clearances, I’m running a 10/30 or 5/30. I have fresh rebuilt engines and the “10” is more than enough, the “5” is what I’d rather have in the crank case, but nothing lighter or heavier if I can. The “30” is right for my engine. The clearances are on in the middle to tight side of the listing.

This ^^^^^^^^

Here's what was posted in:
Oil Viscosity vs Bearing Clearance
and discussed in posts here
Valvoline VR-1 vs. Lucas Hot Rod oil
Your engine builder may have some thoughts on this too.
For street & strip use the following SAE grades:
Rod bearings with
.0015 to .0018 use 20
.002 to .0024 use 30
.0025 to .0029 use 40
.0030 to .004 use 50

For main bearings:
.0015 to .002 use 20
.002 to .0025 use 30
.0026 to .003 use 40
.0031 to .0041 use 50

For general use, its usually better to use a multi-grade.
whateverW Same will provide better lubrication when the oil is not fully warmed up than a straight grade.

Some recommended rod bearing oil clearances for various oil viscosities:
.0015 to .0018 for 0W20 or 5W-20
.0020 to .0024 for 5W-30 or 10W30
.0025 to .0029 for 10W-40 or 15W40
.0030 to .0040 for 15W-50 or 20W-50

For main bearings:
.0015 to .0020 for 0W20 or 5W20
.0020 to .0025 for 5W-30 or 10W30
.0026 to .0030 for 10W-40 or 15W40
.0031 to .0041 for 15W-50 or 20W-50

After break-in, depending on how it was machined, probably best to use a conventional base stock for a few thousand miles.
One current option for a conventional with decent Zddp levels is "Ford Super Heavyduty" meets FORD WSS-M2C171-F1
PETROLEUM QUALITY INSTITUTE OF AMERICA TEST PROGRAM
 
I run 5-30 Castrol Syntec full synthetic, but I have a Magnum roller motor so it doesn't really apply to this thread.
But you answered the question in the title.
laugh2-gif.gif
 
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