What brand of motor oil is best??

What engine? And what is the application?

Everything aside, Rotella T is an excellent oil and has a very good reputation in the on highway Diesel engine group. Between that and Mobil products you really cant go wrong.

Start oil sampling and learn how to read them. If you are running highway you are likely dumping out good oil and overservicing the engine @ 10k services.

 

Check Walmart’s prices on oil.......

 

T4 is like $12 a gallon that's not pricey. The pricey part is the filters. Because I'm not a big shop I end up paying $70 a filter... Unless I find em online for $50

 

If you use Rotella now then you know how much oil you consume between oil changes, switch to Delo for one cycle and see how much your consumption drops; you won't switch back.

Delo doesn't break down nearly as fast as Rotella so oil consumption just about disappears.

 

The wise old owl answered your question. How many licks does it take to get the the center of a tootsy role pop. The world may never know.
I used to use Rotella. When the price of bulk oil was the same as what I could buy it in gallons jugs from a retailer I changed. Made a phone call first. Some new trucks came in with Texaco factory filled stickers. Changed to 15 W-40 Ursa. That became Chevron Ursa about 15 years ago.
Thank it is a good idea to use what you can find on the truck stop shelf or tote a little oil if you are on the road.
Two oil distributors pushed me to go to in house blended oil. I did not but a friend with a fleet did. Do not know it shortened the life of anything but engines ran on it were really gunked up inside.
Only can suggest a tried and proven major brand. Have seen good results on engines ran with Napa (Ashland OIl ). Not saying it has to come from the largest company.
Now I am thanking of changing again. Is there an oil that can replace 15W 40 in an eighties vehicles and work in a 2019 Cummins Pete? Using bulk and jugs now.

 

If it meets the API designation required by the engine manufacturer I wouldn't worry too much about it.

 

I have a 2012 KW T-660 with the MX13. 726,813 miles as of this writing. Manufacturer’s recommendations are if you’re running highway and doing 6.0 mpg you should do an oil change every 40,000 miles. If you’re doing a different application and doing under 6.0 mpg then the recommendation is every 25,000 miles. 40,000 miles sounds crazy to me, and not even the Kenworth dealer recommended I go that much, but I worked for a company called Henniff for a bit and they were very on top of their maintenance and sure enough they were doing oil changes every 40,000 miles back in 2014. Drove one of their trucks and it cracked a sleeve around 540,000 miles (had a 2010 Cummins though, don’t know their oil change intervals). So I use Mobil Delvac and add a gallon of Lucas and do them every 25,000 miles. Amazingly the truck does not burn any oil between oil changes. Many people knock the MX but it has been very reliable so far other then the usual emissions stuff. And make sure to check out Walmart prices for oil, especially when they go on sale, if you’re doing the oil changes yourself. And if you’re leased on to a carrier as an owner op you can get discounts on filters and fluids through their account with Fleetpride.

 

Was using Rotella but the last few changes we've been using wally world brand w/o any issues. Change every 12-15k.

 

try 4 state that's where i buy mine cheapest place around for my isx . i use mobil delvac i have over a mill. on my isx. uses 1/2 gal between oil change every 10k