1995 Chevrolet K2500 6.5 diesel - viscosities?

[Freebore]

I owned an 83 GMC Jimmy with a 6.2 NA diesel and ran it to nearly 200k miles. I owned a 6.5 Yukon TD to 260k miles. Both engines saw various brands of true diesel oils in straight 30, then 10w-30, 15w-40 and 5w-40 oils. Some were non synthetic, others like 5W-40 were synthetic. I used Mobil Delvac 1300, then Mobil Delvac 1 synthetic as well as Caterpillar straight 30, and a lot of Shell (both 15w-40 and 5w-40). The switching of brands was due to availability and I moved to synthetic as it came on the market (and ran it in extreme cold).

Both engines were still original when I sold the trucks (except injectors and pumps), they both still started great at very cold temperatures (-10F) and I was approaching 3000 miles before a quart of oil was needed. I had oil analysis done from time to time and was told I could run to at least 5000 miles but never did go that long. I'm pretty anal about staying on top of maintenance and that carried over to the fuel injection, glow plugs, & starting system. The 6.5 injector pump driver was relocated for the last 100k and that helped. The takeaway I learned is all of the oils work well. All of them will allow long engine life. Spend more for the 5w-40 or even 5w-30 diesel synthetic for easier cold temp starting. I'd be surprised to find fault with any major brand as long as you change oil and filter when you should and use a decent filter.

 

[bullwinkle]

In my experience, oil is not something to stress about in a 6.2 or 6.5. Now as for crankshafts, head gaskets/bolts, even the lower end of blocks (main web cracks)-that's what tends to kill them.

 

[Finn]

Thanks, gentlemen, for your replies.

I must say that for next winter I will be looking for something thinner than 15W-40 - it feels too thick in sub -10 degrees Celsius. Just not sure if the above mentioned Neste semisynthetic 10W-40 would be enough or if I'd like to go with 5W-40. In either case my Webasto will be working next winter but nevertheless...decisions, decisions...

 

[Clevy]

Buy an oil pan heater and plug it in for the colder winter months.
At the time that vehicles manual was written they excluded certain oils because those oils couldn't perform to the degree that others could however todays diesel 10w-30s are more than capable for use in your chev and I would use that grade exclusively to be honest.
Don't some diesels come from the factory with 10w-30 in the sump.
Now as far as the brands you listed devlac and the shell offering would be the only ones I would choose from. And honestly try to find one that isn't DPF approved and carries an older spec. The DPF oils for diesels got neutered just like the gassers oils to prolong the life of the emissions equipment at the expense of the anti-wear additives.
When I'm shopping for oil I try to find stuff marked SJ. That was the last spec where the anti-wear levels of adds in the add pack are still very high. The SM spec is where zddp got lowered.
So maybe look for oils that meet the spec before the latest one. You have no real emissions equipment to protect and your engine benefits by getting a more stout oil.

 

[GSCJR]

Use 10w-30 HDEO when below 0'C and 15w-40 when above 0'C.

 

[Garak]

That sounds an awful lot like what my dad did with his old 6.2 in the day, too.

 

[Finn]

Well, now that the temperatures are again above 0°C the 15W-40 does not feel that bad anymore.

For next winter I will have the broken Webasto replaced and go with a 10W-?? oil.

What surprises me is that I have done probably 1000 km after last oil change and the mineral Neste Turbo LXE 15W-40 is quite clear still - thought it would get black in an instant after start-up.

By the way, when you replace four broken shocks with gas charged Gabriels, put new Hankook Dynapros on, spend two hours to get rid of the camber adjustment prohibiting knockouts and have professional to do a four wheel alignment done this K2500 rides quite nicely. Which is nice.

 

[MaxPF]

MAke your Webasto's exhaust pipe blow across the oil pan. Then you won't have to worry about it