Hi all,
I'm performing my fall oil change (going to winter grade oil) yesterday, and I discover that my kid has used one of my jugs of winter oil (Rotella 5W40) to change the oil in his pickup... Needing to get it done, I decided to use 2 gal of 5W40, and one of my remaining gallons of 15W40 summer oil. Weird thing is, when I opened the 15W40, it looked and smelled very different than the 5W40 I had just dumped in. Both are Shell Rotella T, same service rating, etc. Just curious if anyone else has noticed this or might have any ideas why the 2 oils seem so different?

Please hold off on the flames; I've driven well over 500,000 miles, done all my own maintenance, and I've mixed oil grades in the past in everything from lawn mowers to 900hp injected big blocks with no problems. I've just never seen that kind of difference in 2 oils with same brand name and spec.

Thanks, and glad to be a part of the forum.

 

basically the difference will be the flow ability at cold temperatures being as they are both a 40w in the end

 

5w will flow better than 15w in the cold, no matter if the 5w is a falsely claimed synthetic.

 

I gota deal on some Rotella synthetic blend (it's the gray jug) 10W30, can I run that in my
1st gen?? I got it for her car, but I have plenty and was just currious , we are in a recession

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pca1::

 

Is it diesel engine oil? Diesel engine oil has additives that keep the soot in suspension. Dont use gasser oil (synthetic or otherwise) in a diesel.

 

Thanks Dr. It just says heavy duty, I'm not gona run it. I'll save it fer the wagon
Don't wana create problems we don't need

 

What is the API designation on the bottle? That will determine if you can run it or not.

 

It's acually rated fer Cummins, CAT, and a couple others, so it must be good right??? It's got pics of big trucks n tractors 10W30 heavy duty

 

Diesel oils will have a C rating, like today's oils are CJ-4. Many will also post an S rating for gassers. Typical diesel oils will have a SJ or SL rating. As long as it has this, you'll be fine.