Contour Enthusiasts Group Archives Forums General General Mobil 1 Users

It's not so much of a stability question, as it is a question of letting the acid build-up in the oil sit w/o flushing.

I change the oil out every 5000-7000kms. I do my bike about every 2000kms, but it also rev's up to 12K RPMs, heh.

Acid build-up from where????

Acid is only made when the vehicle is running from H2S (hydrogen sulphide) from the exhaust gases, that combines with water to form H2SO4.

When the engine is sitting there how can acid form out of thin air??

It's a myth.

I go 10k and get an analysis each time.

Combustion byproducts - if you would like I can show reams of engine oil data showing the decline in pH over time (as a result of combustion). Granted the data is all heavy duty diesel, though the same lessons apply. Also granted, gasoline on-highway engines are very light duty, so the combustion byproduct creation is siginificantly less (not to mention the differences in fuel, but that's another subject).

I still go every 3000 miles. I'll occassionaly go over to 4000 or so miles, but not that often. I think I put 7000 miles on the car last year, and that's only because I daily drove it while the Sunbird was down for a while. Now that I've got the SHizzO, I hope to only put ~3k miles a year on the Contour.

Mark

I'm not disputng the decreasing pH of an engine that is RUNNING over time. But the pH will not change from when you park the car at the start of winter till the end when you bring it back out.

You are using DESIEL facts in a gasoline engine?!?!? Desiels vehicles don't even use spark plugs for crying out loud. Oil is going to be used diffrently in each type of engine. Why don't I just put 2 cycle oil in my car....you put that into an engine. Just listen to Sazi and Demon in this site...they seem to know what they are talking about.

I change my oil every 4-5 months which is about 4000-4500 miles. That works out to once before winter, once after winter, and once sometime during the summer.

However the best advice has already been given. Get on oil analysis after your second change (NOT the 1st synth fill) at make your own interval. Make sure your first synth fill is a normal interval beacuse it can clean out the build up of conventional oil deposits.

For example the wife's car goes the same 4-5 months but that is 8-10k miles. Both oils analyze close after the same time period but significantly diferent miles and types of driving.

No, you're missing my point entirely. I agree completely with what you are saying. What I am trying to convey is: I run the oil through the course of the year. As time progresses the pH level drops. As you know when the pH drops below 7.0 you are acidic. If I let it sit over the winter before my next oil change, the acidic nature of the oil will start tend to corrode (admittedly not to the point of burning a hole in the block) metals in contact with it. I change it at the end of the year so that clean, new oil is what sits in the engine over the winter. Does that better explain my point?