Oil change intervals, what do you guys suggest?

[jiggity76]

So I did my first oil change in the 96 CS sedan.  I've always used 5W-30 Mobile 1 full synthetic in my used vehicles including this car.  I also use GM's oil filter, I get it from the dealer. 

How often should I change the oil and filter?  I was planning on doing it at a minimum of 3000 miles but could I go longer like 5 or 6000 miles?  My old 94 Silverado had 238,000 on it when I got it I think and I used guaranteed 15,000 mile 5W-30 Mobile full synthetic in it for 11 years and it had 395,000 miles on it when I traded it off, no engine issues at all.  Again, I used the GM filter and ran it to 15,000 miles every time.

I'm not using the guaranteed 15,000 mile oil this time for some reason, don't know why but just decided to use the regular full synthetic.

Edited January 11, 2019 by jiggity76

[Imp558]

There was a thread about a year ago on that topic, I remember it evolved into oil analysis after Schurkey mentioned having oil lab tested.

[jiggity76]

Ok, I'll look for it.  I'm not sure where I need to go or where I should have it sent off too.  I wonder if local dealers do it?  I'll stick to 3000 miles until I find out.

[pitzel]

Which engine?  I haven't changed oil in my 3.1 in over 92,000km.  Or in excess of 57k miles.  Esso XD-3 0W-30 full synthetic.  Filter changes every 15k miles or so per the manual and use of the double-sized filter.

3k miles, good lord, what a waste if you have a 3.1.

Edited January 11, 2019 by pitzel

[digitaloutsider]

Yeah this is literally the last thread we had repeated lol. For the Regal, I change the oil whenever the OLM tells me to or when I decide "huh.. it's probably been a really long time since I did that".  On average, that's anywhere between 6-8k miles, but the car does a lot of short drives and when it does get driven, it is driven a lot harder than most 3800s are.

The Corvette is changed in accordance with the OLM. 

I use the cheapest Dexos certified synthetic oil I can find and Fram Ultra Synthetic filters exclusively. If I'm feeling particularly sporty, I will add Lubrimoly MOS2.  I have had oil analyses done on both cars which came back with flying colors, so I guess I'm doing something right. 

pitzel, have you sent an analysis out on that oil? I'd be really curious to see what they come back with.

[pitzel]

5 minutes ago, digitaloutsider said:

 

pitzel, have you sent an analysis out on that oil? I'd be really curious to see what they come back with.

No, I should though one of these days.  I had the oil pan off, and there was no glitter nor sludge.  Put the same oil back in the engine and kept running it.  No decrease in MPG per the DIS or manual calculations on long trips.  I started doing the long drains in 2004 after seeing some very good results with the 60degree 3.1/3.4 engines on Bobistheoilguy.  Unfortunately my first attempt was cut short by the dreaded LIM problem in early 2008, but once that was all fixed up and a brief course of flush oil run...  Haven't changed oil since 2008.

Edited January 11, 2019 by pitzel

[digitaloutsider]

My only fear with that (and I can't remember if I brought this up in the last thread or not) would be elevated levels of acid, since oil certainly collects it over time. I'd be interested if there is elevated bearing wear because of it. 

[pitzel]

4 minutes ago, digitaloutsider said:

My only fear with that (and I can't remember if I brought this up in the last thread or not) would be elevated levels of acid, since oil certainly collects it over time. I'd be interested if there is elevated bearing wear because of it. 

The XD-3 0W-30 that I specifically used was dual rated for gas and diesel engines, and as such, had extra additives to deal with potentially higher levels of acid particularly arising from the use of higher-sulfur diesel fuel.   But the sulfur spec on the fuels has been tightened up in the past 10-15 years as well.  Which is where most of the 'acid' comes from.  

In a nutshell, as long as the oil is kept at proper levels, and isn't contaminated by coolant, or fuel I've yet to hear of anyone killing a 3.1 or even a 3.4 due to bad oil.  Heck, I drove a few thousand miles with coolant contamination until I could repair my LIM (just kept adding coolant, it was a slower leak) and that still didn't do anything major except creating a mess in the lifter valley and underneath the valve covers.  

Edited January 11, 2019 by pitzel