How many years can I leave synthetic in before a change is necessary?

[wavinwayne]

Patman,

I agree that GC has probably held up just fine, barring any coolant leaks or excessive fuel dilution. GC is one fine oil.

 

[Whimsey]

quote:

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Originally posted by ekpolk:
I'll join mj in voting for a UOA, and I'd add Terry Dyson's consult too. Your usage is so "non-standard," that I don't think any general advice is going to be much help. Back a couple years ago, someone posted a five year UOA on IIRC a Porsche 911 that saw similarly infrequent use. You should hunt that one up and have a look. Amazingly, the oil was in pretty good shape. Knowing is so much better than guessing or speculating.

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That was my bl's Boxter. It had the factory fill, Mobil 1 5W-40, in it for the 9,000 miles it went in 5 YEARS. He bought it second hand. Had Terry do an UOA and it came back just fine. Low metal wear and the oil still had life left in it. Being a 9 quart sump also helped I'm sure. It's like a brand new car and it runs like a champ. Though I have to say I most likely would have passed on it myself and missed out on a real good deal because of my preconceived notions about OCI's

.

Whimsey

 

[Racer X]

Thank you everybody for your insight and empirical cases.

On your advice, I have reviewed some oil analyses posted by sports car owners who have moderate mileage and multiple years in service, and based on that, there is no evidence that oil needs to be changed every year.

Also on your advice, and to be on the safe(r) side, I will do a UOA when I drain this oil to see what is actually happening in my specific car. I bought a multi-pack from Schaeffer a few years ago, so I am good to go with that.

My strategy will be to go a little past two years, analyse, and adjust the interval based on the results. Going long between changes makes UOA at every change somewhat more economical - I will save the cost of unnecessary changes, plus cost/year for analysis will be quite good, and the diagnostic value of the analysis will be a bonus.

At this point, I am convinced that the recommendation for changing based on time may be a holdover from days gone by. It appears that the oils on the market now are just not subject to "spoiling", barring mechanical failures leading to fuel or coolant contamination, which oil analysis would reveal.

The question of how many years it takes for oil to degrade when used infrequently is still open, but based on the empirical evidence, I'd say it is MORE THAN three times the common recommendation of one year, and probably more for synthetics.

One thing is for sure, we'll have to wait a long time to find out! How many people on this board can resist tinkering with their oil for that long? This could be the most challenging barrier to answering the question! Reminds me of that old Tootsie Pop commercial...

Thanks again, and happy oiling!

 

[ekpolk]

quote:

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Originally posted by Patman:
I'm approaching the two year mark on the oil in my mom's car. I put in GC 0w30 in July 2004, and she only drives about 3 or 4000 miles per year so I didn't want to change the oil that soon, and I have a gut feeling that 2 years will be just fine and the analysis will show I could've probably pushed it further.

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That's about the most potent endorsement a product could possibly receive here on BITOG:

Patman uses this oil in his mother's car for two years! It doesn't get any better than that.

Seriously, this M1 product and GC are oils of similar durability. Remember, there's also a UOA here on BITOG from a Porsche Cayenne that went almost 20k miles on its factory fill M1 0w-40. This is not a "lose sleep" issue.

 

[AEHaas]

Mineral oil based motor oils may form gels that are permanent and degrade oil when exposed to lower temperatures over winter months. Synthetic oils are less prone to this problem. It is a good reason to change oil every spring after exposure to winter cold.

If there is no cold, humidity problem or fuel dilution of the oil over long periods then there should be few issues with long use of the oil. Some advocate changing oil every 3 months or 3,000 miles, whatever happens first. Others say the oil in automotive applications can go for 2 or 3 years. The best answer is probably somewhere in between based on your actual circumstances.

There are reasons to change the oil filter periodically. The pleats are glued together and sealed. There may be degradation over time with exposure to oil and fuels. Ferrari wants you to change the filter every year - for this reason I believe. There is very high flow and they do not want the pleats to possibly collapse or bend into each other from side to side. This would decrease exposed element material and thus impede flow. Some of the base filter media may soften over time.

Gel formation from the cold exposure may diminish filter flow if large enough to get caught. UOA may not be as helpful. It will not tell you everything you may need to know. If it never gets below 35 F and the humidity is controlled and the car was driven to get the engine oil above 220 F each time then 2 years should be fine with any oil and most filters.

I would change the oil every spring however, just because I care more for my cars than the average person.

aehaas

 

[rcy]

GC is in my 4 stroke lanwmower, going on it's 3rd season now. I might leave it in forever. The oil still looks fantastically clean. Lately I've been mulling over draining and refilling with Esso XD-3 extra just because....

 

[jmacmaster]

I'm also not convinced (including by the vague this might happen -- that might happen, unsubstantiated arguments that I've seen on BITOG) that oil should not be left in a vehicle for more than 12 months. I think that the
12-month rule is almost on a par with the 3,000 mi. oil change myth. I put only 7-8,000 mi. a year on my 03 Ford Ranger. Its on its second run of 10,000 mi. with M1 (which I switched to at 9,000 mi. on the truck). On my next oil change I'm going to switch to M1 EP and do a UOA on the old oil. I didn't do a UOA on the first 10,000 mi. run of M1.

 

[Patman]

I finally ended up changing the oil in my mom's 2001 Golf today. As I mentioned, it was last changed in July 2004, so it has been almost two full years since it was last done, and the oil had 7600 miles on it. The sample is now at the lab and hopefully I'll have the results by tomorrow afternoon.

One thing I did notice when I looked at the VW oil filter was that it said 2 years/30,000km on it! So VW feels confident that it's oil filters can last 2 years. And I'm pretty confident GC held up well for 2 years worth of relatively short trips. It's just too bad that we had to add 2L of makeup oil to it, as it would've been nice to see how well the oil held up on it's own without any help.

 

[Blake Sobiloff]

Oooh, I can't wait, Patman! I get about 6K miles a year on my truck with GC and an M1 oil filter (plus FP and LC). I'd love to go over a year with these premium products in use, so your results will be very interesting to me.

 

[Patman]

quote:

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Originally posted by Blake Sobiloff:
Oooh, I can't wait, Patman! I get about 6K miles a year on my truck with GC and an M1 oil filter (plus FP and LC). I'd love to go over a year with these premium products in use, so your results will be very interesting to me.

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I was hoping to have the results before the weekend, as earlier in the week I dropped off the sample from my car and Wearcheck had the results for me in just over 24 hours. But this time around they didn't do it as fast, when I check online I see they left on Friday with only the TBN test left to do. I don't know why they didn't just do it before closing for the weekend? (unless they close early on Fridays for summer hours now?)

 

[Patman]

I got the results back this morning and two years on synthetic is definitely possible! The results looked very good to me, TBN was at 4.90, wear metals were good, I almost feel bad for not letting it go three years!