10w30 vs 15w40 son

25k !!!!!!! You must a mega fleet . No one nor a specialist would ever convince to go that far even with the lab reports. 15k is absolutely MAX with me. My average is 10k-12k period. I couldn’t careless if anyone told me I’m wasting money. For me it’s a peace of mind and I noticed at “My” service intervals that motor purrs……

 

5w 40 full synthetic in everything we run. Cold starting on job sites but still having protection for summer heat are the reasons.

Used to be strictly Delo, until there suddenly became an issue acquiring Delo. I found Delvac, and Sinclair lately. I always believed it best to stick with one brand. Sure hope it doesn't matter now!

Edit to add:

We change oil in the mechanical engines at 250 hours, the heavy equipment per Cat recommended interval of 500 hours, and the pickups when the computer says it's time.

 

I have read that the tolerances are so much tighter in new engines that lighter oil is better suited for them. Frankly though, if the specifications of 15w40 and 10w30 meet the manufacturers recommendations, I don't know if I buy all of that.

 

Our entire fleet runs 10-30... But it is never off the shelf oil. We are somehow hooked up with a major oil engeneering company... They provide us with all the oil, we run it (several different types) and send periodic samples off to a lab. The lab provides us and the oil company with the results.

Its all test oil thats not yet available on the open market... Each type has some funny code name: Goldie Locks, Emily, Princess, Vader, ect. From my understanding each type has a slightly different formulation, I think they are trying to make very specific oils for modern DEF engine.

Edit: we run 50k change intervals... We did 75k intervals for a short time but noticed some bad signs begin to show up on the lab reports, so we went back to 50k intervals.

 

If it calls for 10/30, I’d run 10/30. I’d also watch the oil level closer. I used some thinner Mobil in my Pontiac. Bought it by mistake. 0w20 maybe? Suggested for Honda. Figured if it’s good enough for Honda, good enough for Pontiac. Winter time, and don’t drive it much anyways. WRONG!! It all blew past the rings in no time. That Synthetic burns clean. It never smoked. Cam sensor code came up. It has 3 of them. I just happened to check the oil. Add 3 qts. Cam sensor fixed. The car uses oil. Can get away with longer intervals. At 5000 it needs a quart. So much for only changing oil once a year. I know better, but all the manufacturers have raised their intervals to 7500. I think Toyota up to 10k. The theory is tighter engines need thinner oil. My old Detroit needs 15w40. Go for it, just watch for any new leaks, or burning.

 

I change oil at 12K and that is what cummins calls for with a 5.5 mpg average basically oil wears out based on fuel burned, the dump trucks have about 30% idle time and that is because we are waiting to load or sitting in traffic not sleeper time.
The Lowbed does not idle much but the amount of load on the engine is higher and I still get about 5.5 MPG.
I am not oil brand loyal I think the the specs are so tight on oil that there is not enough difference to matter, I know this will make most of you cringe but I buy what ever oil Walmart has in stock when I change oil I can use 3 different brands the only thing I make sure of is that it is all 15-40 been doing this for decades and never had an lubrication related failure.

 

The engine manufacturers only began encouraging lighter weight oils to satisfy the government mandates for better fuel economy. Lighter oil gets something in the neighborhood of 0.5 to 2.0 % better mpg.
The government doesn’t care about engine longevity.

 

Well .. now you gota start replying to all the posts that are not giving you the answers you wanted to hear and call them naughty names tell them they are stupid and cry to the administration for help because your being picked on .. ..lol
I run Rotella 15-40.. that's just all I have ever used.. ..

 

15-40 Delvac mineral CK-4

Did the CM2250 every 20K. Sold it at 750K all original engine, even the alternator.

Detroits do at 30K.

Old addage was when it uses a gallon it's time to change.

Detroits use maybe 2 ounces in 30K miles.

The higher milage truck is using 10-30 now. Delvac.

Tried that HavBlue stuff once in the Cummins.
Hell to the no. Never again.

I think almost all newer engines recommend the full synthetic.