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94 ETC,97 STS
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3,531 Posts
I wonder what the cost to do a full chemical evaluation on an oil sample is. Not just ph but a full test of all the additives. Probably more than a few oil changes! LOL:stirpot:
 

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1997 ETC (GAVE TO STEPSON 2011), 2000 DTS (RIP)
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1,702 Posts
Discussion Starter #22
zonie - how much condensation can we really have here in the desert with 8 percent humidity? OK, in the monsoon it could jump up to 30%!
 

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95 Eldorado, 2002 Escalade
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11 Posts
I was a lubrication engineer for two oil companies for 24 years. The best way to determine oil change intervals is to submit a sample to an oil analysis lab on a periodic basis. As an independent consumer you would probably pay over $25 for this analysis. Half the cost of an oil change for sythetic.

All of the above posts are valid, but just consider that anything can happen over time, such as a coolant leak, which is often catastrophic and an oil analysis may not predict. With a proven synthetic like Mobil 1, oxidation is usually not a factor. It has an excellent additive package which is not normally depleted.

The benefits of sythetics are numerous, even at 4 to 5 times the cost. In cold climates the oil feeds the upper engine more rapidly than mineral based oils. In hot climates oil degradation is much less than its mineral based counterparts.

In my opinion, miles, and how they are driven, are more important than time when determining an oil change. I put 287,000 miles on an 87 pathfinder, 3.0L, used Mobil 1, and changed oil every 20,000 miles. Average mileage was 3500 miles per month. This was the optimum oil change interval when contaminants and wear metals started to approach oil change limits. I never had a physical oil condition, such as viscosity increase/decrease, oxidation, contamination, or additive concerns. I submitted an oil sample about every two months, 6-7000miles.

Filters are also a factor. Buy the best you can. They can deteriorate under high viscosity loads, high contaminant loads, etc. Once you blow a filter and create a bypass condition, all bets are off. You will notice decreased oil pressure if you have a pressure gauge.

Hope this helps. It is hard to make a general recommendation due to the variety of conditions an oil is susceptible to experiencing.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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71,670 Posts
Blackstone Labs charges about $25 + your sample postage for spectral analysis, additives, solids, a couple of others. Plenty of info for the average gasoline engine test analysis.
 

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94 ETC,97 STS
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3,531 Posts
zonie - how much condensation can we really have here in the desert with 8 percent humidity? OK, in the monsoon it could jump up to 30%!

I agree, my point was how does time affect the other components in the additive package? I don't know and I'm not paying to find out so I just change oil more often.
 

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95 Fleetwood Brougham / 01 DTS / 11 CTS Lux / 11 DTS Platinum
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7,085 Posts
The crankcase is not sealed, far from it actually.

On the other hand it sounds like if you just drive your cars more this wouldn't be an issue. go ahead and put 15k a year on the car then there wont' be any question about why or when to change the oil.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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71,670 Posts
Lots of ideas, but maybe a Moderator will move this into a new thread titled "Exhaust system for 1997 STS ?"

If you go into a running thread with questions far removed from the topic that's "hijacking" - not bitching, just informing.
 

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2010 DTS
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87,729 Posts
3000 miles! That is 1960's advice. Jiffy Lube will still tell you that for obvious reasons. With today's oils and engine technology you can go much longer. Your car (and most) have an oil life monitor that will tell you when to change oil based on your driving conditions. It is very accurate and has a 100% safety margin built into it. Pre 2000's where capped at 7500 miles and the 2000+ is capped at 12,500. You can trust it. Do a search for OLM or Oil Life Monitor and read up. 3000 mile changes are a waste of time, money and oil.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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71,670 Posts
riph, Have you ever toggled through the DIC messages to look at your OLM ? If not, who is resetting it at these 3,000 mile ( :eek: ) oil changes ??

As Ranger posted, we're a long way from "Kendall, the 2,000 mile oil !".
 
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