rotella 15W40

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Scrubcadet10

Scrubcadet10

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As some of you may know, some people use 15W40 Rotella in their small air cooled engines due to the additive package being better than standard automotive oil.
however it's rumored on a small engine forum that rotella is no longer as "potent" as it used to be, as far as zinc and phosphorus and other anti wear additives go.
is it true? are they removing/lessening the amount of those?
 
From what I’ve seen, the T6 full synthetic version has cut back on zinc and phosphorus. The T5 blend still has decent amounts.
 
Rotella T 15w40 used to be a good oil for '60s cars after ZDDP levels were reduced when cats came in.
The numbers matching guys have switched to the boutique oils with elevated ZDDP levels, around 1200 PPM or even more.
If you do not have higher valve spring pressures, Rotella T should be fine or any decent 10w30.

I don't use it anymore...
 
they’re all chilling around 1100ppm

edge 0w40 matches that, m1 15w50 has more but they’re obviously premium products
 
Last edited:
Scrubcadet10 said:
As some of you may know, some people use 15W40 Rotella in their small air cooled engines due to the additive package being better than standard automotive oil.
however it's rumored on a small engine forum that rotella is no longer as "potent" as it used to be, as far as zinc and phosphorus and other anti wear additives go.
is it true? are they removing/lessening the amount of those?
Click to expand...
just get castrol gtx 15w40, alot more additives than the newer rotellas
 
Scrubcadet10 said:
As some of you may know, some people use 15W40 Rotella in their small air cooled engines due to the additive package being better than standard automotive oil.
however it's rumored on a small engine forum that rotella is no longer as "potent" as it used to be, as far as zinc and phosphorus and other anti wear additives go.
is it true? are they removing/lessening the amount of those?
Click to expand...
What's better, potency or stoutness of an oil? Since it's only "rumored" then maybe they are equivalent.

Or is a "slug of boron" or "dose of zinc" better?
 
kschachn said:
What's better, potency or stoutness of an oil? Since it's only "rumored" then maybe they are equivalent.

Or is a "slug of boron" or "dose of zinc" better?
Click to expand...
I mean modern small engines work great on lower additive oils, no point in using alot of money on an oil with alot of additives, a cheap 15w40 would work very well, I myself would even use 10w40 in a small engine, it all works.
 
blufeb95 said:
https://pqia.org/castrol-gtx-sae-15w-40-diesel-motor-oil/
Nope, it appears to have even less phosphrous than the typical rotella package, the highest phosphrous/zinc oil I know that's on the shelf is Delvac Extreme 15W40 which has around 1200ppm of phosphorus which is the CK-4 limit.
https://bobistheoilguy.com/forums/threads/mobil-delvac-extreme-synthetic-15w-40.328571/post-5621690
Click to expand...
Totally Agree.

The only other oil I'd recommend would be Ford Motorcraft Superduty Formula
http://pqiadata.org/Motorcraft_15W40.html
 
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