That is correct.....tough oil and I run it in ALL my vehicles. Try running Mobil-1 10W40 motor oil in a cummins.....lol.......won't happen. Speaks volumes of why Rotella is that good for a race engine. Just ask some of the turbocharged sled pulling Diesel's and they will tell you.

 

Yea, Shell Rotella is pretty much the gold standard for diesel engine, but I have never heard of running it in a gas engine before?

Also, is heat the only thing that thins out oil? Why is thin oil bad?

 

It doesnt lubricate as good.

 

No heat is not the only thing that thins out oil fuel contamination will help break down oil so that it can no longer hold its viscosity to designed limits. And while there is nothing wrong with thin oil as a mater of fact that is why oil companies started making multi-viscosity oils such as 10W30 etc... It is supposed to flow like a 10w oil when cold and a 30 weight oil when hot basicly. I am not an expert on oil I just know what they are supposed to be doing that is why noone runs strait 30w etc... any more. You want thin oil on start up and a thicker oil once it warms up I know everyone knows that is the basic design of multi-viscosity oils just reminding you of it. But to thin of an oil for a certain application can become a problem by leaving no film of oil between two contact points such as a rod bearing and the crank. Under a load thin oil will displace faster and easier than a thicker oil leaving little or no oil barrier between the two and thus causeing more wear etc... 99% of all cars should be running a 10W30 for extreme applications a 10W40 is the next best thing when you get into racing applications there are a lot of choices to consider although for the most part all of us street/strip guys should be running a 10w30 or 10w40. I am running a 5w30 right now with no issues I will switch once I get a few miles on her and start pushing a lot more power I'll switch to a 10W30 and have it sampled after a few miles and see if I need to switch to a 10w40 or not. Good luck guys. If you really want to know more about oil and what you should be running you might do a search there are a couple of oil experts on the boards I used to read a lot of there information and they have facts to back there recomendations but with a lot more acctual experience than I had in this one incident. 2redgmc also works for Royal Purple and can help some of you that are really worried or don't know what to do he can give you the technical info some require.