Oil change time

[4NDELIT]

well it's been another 3K miles (up to 73K now) and it's time for another oil change. I change my own oil, and I just wanted to complain about it because these cars are rediculously messy when it comes to oil changes. First off, the drainplug takes a 14 mm allen key, which is hard to find. Next, the drainplug is rather large, so the 9.5 quarts it takes comes rushing down all at once. Finally, the oil filter is located on the bottom of the car, so when you replace it, oil comes gushing all over (almost impossible to get all of it in the pan I use). I really hate doing this, but I love my car enough to do it myself. Just wanted to complain.

[Gilly]

Complaint noted.

Gilly

[4NDELIT]

the only good thing about changing your own oil: after you get oil all over your hands, they feel silky smooth. It's like lotion... for guys.

[Richard1]

Oil changes every 3,000 miles is a conspiracy involving Jiffy Lube and oil manufacturers. It's unnecessary.

[Richard1]

according to a fellow mb fanatic, who's mechanic tells him every 7k....that said, I do an oil change every 3k as well.

[4NDELIT]

when I changed my oil, it was pretty black... with an old car like this, I'll stay with 3K miles

[nhodges]

It's your money and your car. Unless you are buying your fuel in "TJ' you are wasting your money to change the oil @ 3000Mi. It' your car and your $$$. Happy motoring.

[Gilly]

In my opinion, the mileage between oil changes should vary somewhat depending on the crankcase capacity (oil volume). The more oil, the more crud it can suspend, just stands to reason.
For most people, assuming combined city and highway driving, I recommend 1000 miles per every quart of capacity. So most domestics, holding 4 or 5 quarts, means 4000 to 5000 miles. On MB's, most hold more than that. Most V8's hold 8.5 quarts roughly, so 8000 miles or thereabouts doesn't seem unreasonable.

Gilly

[4NDELIT]

so my car should last 9500 miles between oil changes? I think that's a little excessive... my oil was really black coming out, and that's at 3K miles, I don't think it'd be good to let it last for 9.5K...

[Gilly]

Mmm, that engine should hold 8.5 quarts, not 9.5.

WHY think that an engine that holds 8.5 quarts of oil should have the oil changed at the same amount of miles as one that holds 5 quarts for example? Makes no sense to me.

If you want to go by "how black the oil looks", fine, y'know, it's your car, pull out the dipstick every 500 miles and when it looks "black enough" to you , change it then. I prefer to go by miles.

Every quart of oil should be able to suspend a cetain amount of contaminates. An engine containing 8 quarts of oil should be able to go twice as long as one that only hold 4 quarts, just as surely as a car with a 20 gallon fuel tank will go twice as far as one that has a 10 gallon fuel tank (assuming the fuel mileage is the same).

Gilly

[4NDELIT]

Originally posted by Gilly
An engine containing 8 quarts of oil should be able to go twice as long as one that only hold 4 quarts, just as surely as a car with a 20 gallon fuel tank will go twice as far as one that has a 10 gallon fuel tank (assuming the fuel mileage is the same).

Gilly

that last part is what concerns me. If my car runs proportionatley dirtier than other cars with less oil (which I'm sure old cars and bigger engines do), I would expect to change them at the same intervals. Also, it does say 8.5 in the manual, but in practice, it takes 9.5, I'm not sure if the manual doesn't account for the filter or something else...

[Gilly]

Well I certainly wouldn't change that much oil every 3000, that's for sure. 5000 minimum, at least 5000 miles between changes, or once a year.

The amount should be 8.5, that'll put you in the middle of the normal range, right where MB wants it. You can probably get another quart in there and it'll be at the "Max", but MB doesn't WANT the oil at the MAX line, they want it about in the middle of the operating range.

Gilly

[4NDELIT]

that could be it, but I have a slow oil leak, so I like to leave it high. Thanks for clearing that up though. As far as the 5000 miles, I think I'm still gonna go for 3, because it doesn't make too much difference in cost, and it's not like it's doing the car any harm

[kip Foss]

If one goes by the color to determine the frequency of and oil change then I should change the oil in my Diesel truck every 500 miles

To change your oil at anything less that 5K and preferable 10K is an absolute waste of time, effort, natural resorces, and money. If you feel guilty, change your filter every 3k or so but any good, name brand oil will go 10k between changes. In my 60 years I have driven many, many cars well over 100k, and some over 200k, and have never ever lost an engine or even had a minor oil related problem.

The 3k oil change is basically a conspiracy between the manufacturers and the oil companies. The makers cover their collective asses by making sure that even if you forget an oil change 6k miles is probably the maxium you will run w/o a change. The oil companies, of course, make a bundle on the sales of large quanties of their product.

Name brand oil, good quality filters, and driving you car until it is up to temp. are the three things that make your engine last.

[bobw]

Originally posted by 4NDELIT
the only good thing about changing your own oil: after you get oil all over your hands, they feel silky smooth. It's like lotion... for guys.

Used engine oil contains allsorts of combustion by-products and other nasty stuff. I've read that it's potentially carcinogenic. For years I used no protection when changing oil but I now use latex gloves.

--
bobw
1983 380SL
1991 BMW 735iSE