Nice read. There is a lot more to a viscosity measurement than pouring a fluid out of a tube. I have measured many different silicone fluids and brake fluids with and without fillers, and between -50c to 200c using a viscometer. To get reliable and accurate data requires much more than mythbuster techniques. There was no mention of a viscometer in the entire article. Naming your equipment and test procedure is engineering research 101. I couldn't publish a paper or write a patent if I didn't disclose my testing parameters.

His data on "zone of protection" is questionable. Saying that 15w40 doesn't protect until 120C is incorrect. As a designed diesel oil, I think engineers would use an oil that would protect a diesel engine at operating temperatures which is lower than gasoline engine operating temperatures. So either he's wrong or the entire trucking industry should switch to 0w20. Could this perhaps be only legitimate data for a corvair? I also find it interesting that formulation AND manufacturer AND SAE rating seem to combine to give the actual viscosity. Too bad he didn't test RotellaT 15w40 or syn 5w40. If anything that has convinced me to run the Rotella syn 5W40 all year round.

Light oils produce better mileage. If you can adequately protect your engine (and it was designed for) a light oil, go for it. I use mobile1 5w20 in my car.

 

Wow you guys are great! Cherokeeforum is way more helpful than jeepforum!

 

Cool, as I said above the chart speaks for itself.

 

First I will say that I have no scientific basis for what I am about to say so I'm sure there is nothing to it. But all I can say is both me and the guy I work with started running 15w40 oil in our vehicles because we got it pretty much for free (My 94 XJ and his 89 Town Car) and we both had our head gaskets go out within 6 months.

 

I worked for a big truck fleet from 88 till 07 we ran various brands of 15-40 in all of our support veichles over the years and never had any motor problems. we had mostly ford 4.0 straight sixes and 302s some chevys and 1 nissan some of them had close to 300.000 on them . im switching over on my next oil change on my truck i just changed the oil in my 69 rr sounds fine . another thing ive learned over the years with this weight of oil it will protect the motor when overheated where thin oil usually wont.

 

Lots of good info. Didn't have time to read full detail but I seem in the begining talk on zinc. To bring your zinc levels back up ad a bottle of blue STP oil additive. It has enough to bring your zinc levels back up to where they were back in the 60's era oil

 

I think im going to run rotella 5w40 syn and a puralator filter, still open to suggestions! lets keep this thread going, its very informative

 

Like the good Dr. said, the 1st number is more important than the 2nd. 0W40, 5W40, 10W40, 15W40 and 40W are the same vis at operating temp.

 

LOL you are obsessed with that dude!

 

Great choice. The t6 is even synthetic.

 

Good choice. Keep in mind that even though some argue that ZDDP is not needed in an engine that is already broken in, I would say that it is still needed- at least in smaller amounts as a general anti wear additive. Just about all major car motor oils (not diesel) do not have zinc in them anymore. Thank the tree huggers for that.

 

A lot of high horsepower drag racers use Rotella.

 

Uhhhhh... I may suggest you take a look at some VOA's or UOA's before making the statement that "Just about all Major car motor oils (not diesel) do not have zinc in them anymore." Click the link in my signature for bobistheoilguy forum thats a direct link to there VOA forum.

VOA= Virgin Oil Analysis
UOA= Used Oil Analysis

I do not know of any motor oil company that does not have Zinc in their fluid. Lower levels absolutely but they make up for it in Moly, Titanium, etc.. I love a great oil discussion so let me know if you have any other questions.

 

Ford 4.9 straight six

 

Sorry I should have said less ZDDP. Those samples, at least the first post, are from 2005 before most motors would have removed the majority of zinc so they are obsolete. I didn't see any recent VOA of common oils. Another poster said that if the VOA is over a year old it means nothing... is this true? Could manufactures change formulations that often or have such bad quality control?

So the question is does moly, Ti, etc... fully make up and act the same way ZDDP does for engine lubrication?