Mixing oil weights

At the end of the day...IMHO...as long as the engine HAS enough...it's not the end of the world...although I personally would prolly go with the lower viscosity oil in an emergency.
Tolerances are much closer, as noted by a previous post. Just keep 'er full.

 

Detroit allows 10w30 thru the entire year in every engine they make including the legacy engines like the Series 60 and MBE according to their 2016 Lube Oil, Fuel, and Filters manual. I have been using a syn blend 10w30 Schaeffer, similar to the Delvac Elite 10w30 syn blend, and doing my normal 20,000 - 22,500 mile oil changes and used oil sample numbers look as good, and in some cases better, than any 15w40 that was in the engine early on. 563,000 miles on the factory reman, and the oil samples look like they came from a young engine.

Ambient temperature is not as big of an issue as it is with air cooled engines. My oil never exceeds 200F on the hottest days under the hardest pulls. A 10w30 will handle that just fine. The oil actually shears less than the 40w oils I have used before over the oil change interval. Many others over at the BITOG oil website have noticed the same thing. A 10w30 seems to actually be more shear stable than a 15w40. As far as oil pressure goes, the 10w30 I have been using just shows about 2 PSI less over the temperature range compared to any 40w. That doesn't concern me as viscosity of an oil is actually a measure of resistance (when you see Isaac Newton in the next life, ask him about it), not "thickness", so a 30w oil is going to flow better than a 40w under all conditions. That can be a good thing. While higher pressure gives the impression of oil getting where it needs to, resistance to flow is also a factor in oil pressure. When a motor is working hard, I want a good flow of oil getting into every little place that needs oil.

Back to the mixing weights, within the same brand it will not be that big of a deal. I wouldn't mix weights from different brands, as add packs could be significantly different and conflict.

 

I have watched oil temps begin to rise after the Pyro does. Then the coolant begins to rise. Then there is a possibly of a problem halfway up the 20 by something percent grade. If it's working really really hard that oil temp WILL rise inside the engine.

 

Of course it will, that is why the engine has an oil cooler. My oil temps do not rise as the pyro does. My pyro is up down, all around, as I pull a grade, coast down the other side, etc. My oil temps virtually mirror the coolant temp.

 

Sure Cowpie1, Im referring to a more extreme pull on the older engines in my time where the pyrometer was a important gauge to follow if not the most important during the pull that might take a while.

I love engines that can cool the engine oil no matter what you do. That means you can flog em that much harder if there is a need.

 

I do follow the pyro pretty closely with my pre-egr S60. And really, when it comes to discussions like this, what went on back in the day really is not relevant. Kinda like discussing how we fought in Viet Nam and what we had to fight with compared to the how the younger crowd deals with the present threat we face.

 

Yea and that makes for a very good thougtht there.

I do not want to think that the old days are gone forewever making me a museum piece. The young ones today (21 to 30) they need some exposure to what was once so they understand why the new trucks run the way they do. Does that make sense?

 

Thank God someone put this post back on the rails! If you don't have the exact oil you want...put some IN. Drive.
..change it whenever....and go on...! Sheesh
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