Gas Engine PCMO Oil Color Question

[SWS]

Many have stated on this board that oil color doesn't matter - that oil that has turned black is just doing its job and is not an indicator of oil wear. I accept this to a point. However, turning this around, I wonder if anyone has had an experience where the oil has NOT changed color but it was found to have degraded / worn-out?

I switched from Dino to M1 last Spring and am on my second batch of M1 in 2 cars, the first batch was a short OCI. I observe after 5 months of mostly in-town driving that the oil on the dipstick is still clean! Is this reliable evidence that the oil is still good?

Thanks for your comments!

 

[ROM]

Nope. How many miles are on the oil? A UOA is the method of choice for determining an oils effectiveness.

 

[SWS]

Each of the cars has about 5000 miles on this batch of M1.

This lack of color change is amazing to me since Dino would have changed color significantly by now in these cars.

 

[olympic]

Oil color is closely tied to oxidation so since synthetic oil is more resistant, it makes sense that it would stay clean looking longer. I've put as much as 10k miles on quality syn oils and they were still transparent on the dipstick.

 

[TallPaul]

I am thinking of dirty oil in a different way, like when I do a blotter of a few drops and get black stain in the middle. I put Valvoline Synpower in wife's Aerostar and in 1000 miles it is looking pretty dirty. But I have heard the first run with synthetic will do a lot of cleaning and maybe get dirty fast.

Olympic makes an interesting point though. I wonder how would one know if the oil is getting dark from oxidation or from cleaning out the engine? Durablend was running fairly clean in the above mentioned Aerostar. Then I ran a load of Maxlife and it ran dirtier, but the worst so far is the Synpower. (All per the blotters.) If the oil stays clean, either it's not cleaning or the engine is so clean that there is nothing to clean?

I'm not helping SWS, am I?

 

[olympic]

He poses a good question. Can clean looking oil still be degraded enough to need changing? I'd have to say no but there probably are exceptions.

 

[Michael Polutta]

I would think (oops, that's dangerous) that in a bypass-filtration scenario it could look clean but have no additive life left. Likely that TP filter changes and subsequent oil top-up would replenish, but it COULD happen...

 

[Gene K]

So oil color change in Gas Engines is from Oxidation?

I believe in Diesel Engines it is from Soot Loading?

Gene

 

[Al]

Some of this goes back to something I mentioned before. It woujld be nice to have a standard form to use for our oil analysis postings. Oil appearance could be one of these pieces of data.

 

[radiometer]

Through the '80s I was driving a 72 and a 66 VW Beetle. I used the same GTX 20W-50 oil in both cars. The 66 always turned the oil black in a short time, while in the 72 the oil remained clean appearing much longer. I always changed at 3k. Even after I had the engine on the 66 rebuilt it continued to turn the oil black in very short order. Same oil, same cheap gasolines. Same kind of driving.