300SDL oil change interval on Rotella T5
 

I guess the title says most all of it, I had been changing at 4000 on the standard diesel dino. Thursday I’m embarking on a 2000 mile round-trip. I put in Rotella T5 15/40 3400 miles ago. Not sure if 5400 miles is an acceptable interval.

It's cheap oil. I'd change it every 3k. Mobile 5w40 is awesome for these cars.

I don't think a road trip is as hard on engine and oil at the jotting about town with a lot of stop and go. Anyway, I almost never go further than 25 miles so I change the 617's oil ever 3000.

If you change it now you won't have to change it when you get home.

Isn't T5 a synthetic blend? If so, you should be able to do 5K without any worries. I'm sure lots of folks have gone longer on worse oils and their cars lived to tell the tale.

Unless the oil has seen almost all city/idling/short trips (less efficient driving conditions) I'd run it. I've put T5 in a couple engines and it seemed to perform very well.

Thanks for the feedback. T5 is a synthetic blend, this is my first time using it, O'Reilleys has it on specials for about the same as dino. About half of my driving is freeway commuting. And, not scientific, it looks lighter at this point than did the dino.

7500 miles.

Never change your oil, even synthetic, at 7500 miles in a 30+ year old diesel. Use quality dyno/synethetic 15w40 and change every 3k miles. When the car was brand new in 1980's, and the engine was new, it was okay to follow this recommended service interval 5000miles+. These engines are decades old and have hundred's of thousands of miles on them.

Doing an oil change is the most inexpensive maintenance item you can do, do it early, use quality parts, and have peace of mind.

And chemistry has come light years. If these engines gained their reputation for longevity on 70's dino oils @ 5K intervals, there's no reason an interval close to that with today's oils won't keep a healthy engine together just as well.

The main concern here is protection of the piston rings. I don't agree with everything Kent says or recommends but he is 100% with recommending an oil change at 3000miles MAX.

Yes we've come a long way in oil chemistry and such but these engines have hundreds of thousands of miles and are 30+ years old. Change your oil every 3000miles or 5000KM.

https://www.youtube.com/watch?v=y4VqcghARzg

I usually do between 3000-3500. Oil and filters are cheap.

230k miles with 10k mile oci, 400+ psi compression on all 6 cyls even with a cracked #14 head on cyl 4, 5, 6, and zero chain stretch. I'll let you know when 10k mile oci kills it.

Very nice I do the same. There's nothing less expensive then a quality oil change and filter. It's shocking some people run their oil changes to 10k with blown heads.

Some people have absolutely no respect for their Mercedes-Benz. Why not fix the head if it's broken and continue to drive on it?

Oh spare me the bull**** and read your owner's manual. Better yet get an oil analysis done, do a compression test, measure timing chain stretch, check your oil consumption. The flaw in the #14 head castings have nothing to do with oci.

An oil change is good until the pollution level increases, the detergents wear out, or the viscosity begins breaking down from heat and age. With the amount of oil these engines circulate, you can get away with some decently long oil changes if you use decent stuff. Even the cheapest Wal-Mart branded dreck in a jug is better than what was available in 1986.

Claiming someone with an OM603 is abusing their engine because of a cracked head is absolutely ridiculous. The early 603's with the #14 head casting are prone to cracking, even if maintained by the book and with your anal-retentive style of maintenance flushing money down the toilet all the time.

Before claiming people don't respect their cars, learn to respect your other forum members instead of spreading FUD and misinformation.