Oil Change

[347stroker]

When I had my truck or other high performance car I used oil that was manufacturer recommended so as not to void any warranties. Believe me when a thirty thousand dollar caterpillar goes down the first thing they do is pull an oil sample. Now most of our engines are not stock and to varying degrees modified. That is the info I'm after. The oils and viscosities to use. My engine dynoed out at 420 hp. I think that is pretty fair for a small block. I just need the info to make a wise choice of oil. Tom

[601HP]

And as a result of today's plethora of info, we are able to make informed decisions regarding the oils of our choosing. There are many oils to choose from. I learned a bit AND I reached the point of TMI (too much information) today.

This website often reflects its value to us.

David

[bobcowan]

Originally Posted by 347stroker

Again I'm learning what I need to know about oils. The first number is the cold viscosity and the second number is the hot viscosity. Please correct me if I'm wrong or steer me to a site that explains it. To

Yes, that's essentially correct. Keep in mind that viscosity is highly dependent on temperature, and is measured at standard temp. As the temp goes up, the viscosity goes down.

The second number is the viscosity at operating temp. For lab purposes, that's 100*C. That doesn't mean the oil will have a viscosity of 40 at operating temp, though. What it really means is that if you had a 40wt oil at standard temp, and then heated it to 100*C, this is what it would be like. The actual cST viscosity at 100*C is somewhere around 15.

A UOA will report that for you. As the oil wears out, the viscosity drops.

Used Oil Analysis - Bob is the Oil Guy - Bob is the Oil Guy is a great place to study tribology.

[347stroker]

Bob thanks for the info. Due to EPA regs big diesels had to have a particulate filter. That supposedly keeps soot out of the atmosphere. They are expensive, reduce fuel mileage, and cause a host of problems. I was not going to spend 20k to retrofit my Peterbilt so I got out of trucking. I'm going to see what oils are available for my application. I'm strictly street. Tom

[Z-linkCobra]

This thread was a good read. Like another on here I think I have too much information now....lol.

[RET_COP]

that post and his testing procedure by 540 Rat has been questioned by many people FWIW

[bobcowan]

Originally Posted by RET_COP

that post and his testing procedure by 540 Rat has been questioned by many people FWIW

Testing is always questioned. As it should be.

Unfortunately, most people who scream the loudest have a reason for their question. Like their favorite oil was listed as #98. Or they work for Royal Purple. Or whatever.

No lab testing is ever going to be perfect. It's never going to predict exactly what the oil will do in your engine during your use. You have to evaluate the testing procedures and decide what makes you feel warm and fuzzy. Then put the oil in your engine and run it for a while. After that, a UOA will tell you if made the right choice or not. Unfortunately, that kind of testing can get expensive.

I look at all testing with a grain of salt. And I look at all complaints about testing with two grains of salt.

I have never done a UOA on my Cobra engine, because I change the oil so often. But maybe I'll do it this year just to see what it looks like. I've done it for my other vehicles, and have found it to be very valuable.