Oil

I change the filter and add a quart every 6K miles using Mobil-1 Synthetic. I personally don't believe that any filter is good for 15K miles.

my2¢

Why?

Are you relying on some structured documented testing, or are have you just decided on a arbitrary number?

What criteria do you use to determine at what mileage an oil filter stops filtering? What tests/criteria do you use to determine at what mileage your oil stops doing its job? Why is it good for 6000 rather than 3000, yet not 15000???

I use Mobil One every 6-7000 miles. Most auto manufacturers recommend 5000 on an oil change unless under extreme driving conditions and then 3000. If you look at their definition of extreme. The vast majority of people driving don't need to change until 5000. Oil change companies go "safe' to get you in their shops almost twice as often. As far as the 6-7000 I do, I've got a 120k mile LT1 that I want to last a lot longer and figure the oil change is my least expensive insurance. As far as the 12,000 mile oils. I spoke to an Amsoil rep at the NCRS Winter Regional a couple of years ago and they were promoting their 12000 mile oil. At that time, their recommendation was to change the filter every 6000 miles and then top off to replace any lost in the filter change. Rob

I'll raise that to 4cents. I like Dad's and Key's annual change with a filter change based on mileage and how much dirt I think the engine swallowed up. My '02 went 7K miles this year. The C4 is now a 'commuter' and runs about 12K miles a year. Same rules happen to work for both cars. I check oil every couple of weeks and top up as needed.

As far as why change any earlier: 1. High mileage engines have more blow-by. The lube oil carries a larger load of gasoline, combustion crap and other goo. 2. Large engines that go on lots of short trips don't warm up, screwing up exhaust systems and lube oil. I try to drive the 'vettes >20 miles each time they are started.

--PJ '89 auto coupe, '02 6-spd coupe

testing by whom ? the oil filter manufactures ? get real...

I am relying on 41 years expierence changing oil.

years back, had an STP filter (used in a pontiac lemans) decenagrate and stop up completely up after 4K miles. but, hold a new oil filter in one hand. hold a used oil filter in the other hand. which is heavier ? why do you think one is heavier ? the more miles on the filter, the heavier it gets.

clear oil or dark oil ? why is there a difference ? which would you prefer.

reguarding synthetic

3K would be a waste of good $$$'s 6K is not too dark. 15K is damn near black.

my2¢

-- "Key"

I posted part of this article some time ago but I figure it won't hurt to do it again:

Synthetics are not new. A researcher named F. W. Sullivan of Standard of Indiana had an active research program underway in the 1930's. During the Battle of Stalingrad in 1942, lubricants jelled in the extreme cold, stopping the advance of the German tanks. The Germans then developed synthetic lubricants for cold-weather use. After the war, developers of the then, new jet engines found that mineral oil lubricants wouldn't stand up to the jets' searing heat. Esters solved the problem, and today are used in all jet aircraft. Synthetics began to get attention as crankcase lubricants in the

1960's when the Army was trying to find better crankcase oils for Arctic use.

Car owners were once directed to change oil every 500 miles. Slowly, as oils got better the change interval grew to 1000, 2000, 4000, finally 6000 or

7500. All on mineral oils. Mineral oils could undoubtedly be used under some conditions far longer than they are now. Auto companies are conservative in their oil change recommendations so that even those hardest on their cars will have trouble-free service. Auto engineers work closely with oil company engineers in developing drain recommendations. Since Mobil is one of the major oil companies and doesn't want to upset its relationship with the car makers, it is not claiming extended drain capabilities for Mobil 1 in its ads. Yet Mobil researchers clearly believe it can go much longer than the drain interval specified by Detroit. How much longer? Mobil shows data on taxi fleets that ran 50,000 miles with oil drain every 12,000. The torn down engines were super clean and showed normal wear or less.

FOR THOSE OF YOU WHO WOULD LIKE TO READ THE ENTIRE ARTICLE try to find : Popular Science April 1976

OR E-mail me and I'll forward it to you