DieselAddict's secret oil change revealed!
 

Ok, so maybe the following isn't secret to everybody, but I'm sure not everyone knows it. I've heard people saying on this board that their oil is still black even after an oil change. Well, today I did an oil change using the following method and my oil is crystal clear even after driving the car for 30 miles.

1. Warm up the car so that the oil is at normal operating temp.
2. Lift the rear of the car so it's higher than the front and shut off the engine.
3. Remove the oil filler cap and oil filter. Let the car sit for 5 mins.
4. Without restarting the car, lower the rear and lift the front so that the driver's side is lower than the passenger side.
5. Drain oil.
6. When it's all out (only drips) add some fresh oil to filter housing and to engine.
7. Wait for the oil to come out and do nothing until it just drips again.
8. Repeat #6 and #7 until the oil comes out clear.
9. Install new filter and refill engine with new oil.

The purpose of lifting the rear is to get all the oil out of the upper oil pan. I use ramps for this purpose and then for step #4 I just let the car roll off the ramps and use the jack that came with the car to lift the front passenger side. Comments, questions?

I won't tell anyone....promise.

Clear after 30 miles is truly amazing.

Once in a great while, I have it clear on the initial dipstick, but never after driving.

Don

What's happening to the oil in the cooler? Shouldn"t it be blackening all the rest of the oil when it mixes in? Is the thermostat in your oil cooler stuck shut?

Kerry, you make a good point there, but I've been doing frequent oil changes with lots of flushing (but without the lifting of the rear), so my soot was already quite diluted before today's oil change. Now that I got my oil totally clear, I'll extend the drain intervals a bit. If your oil is totally black, it may take more than one oil change to clear it up completely.

Seems like a waste to me to flush a little bit of old oil out of the engine with a few quarts of new oil.

I drive my car for atleast a half hour until the engine is completely warm, park it, let it idle, get all my goods together then turn the engine off and drain the oil. Let it drain for a half hour, change oil filter, and fill.

I'm with turbodiesel both on the hot change and the use of oil as solvent. If you want to flush, just pour some diesel fuel through it after the oil has drained some. Diesel fuel is about 25% of the cost of oil and serves as a solvent rather than just oil. Let the diesel then drain for some time before putting it all back together.

Also, having seen the inside of 616 and 617 oil pans I can't IMAGINE how raising the car can drain more oil out of the upper pan.

All that said, regardless of your particular method, you are doing the right thing in changing it hot and taking steps to change it thoroughly. Now that it is clean, depending upon your driving habits, hot overnight oil changes every 3,000 miles or so should keep it clean.

Good luck,

Actually, I usually don't use more than a quart for flushing. The highest I've ever gone is 2 quarts. At about $1.50 / quart, that's not a waste of money in my opinion.

Larry, I was actually wondering myself about the upper oil pan and whether lifting of the rear can help drain the oil out of it. Well I tried it and I'd say I got about half a quart more out of the car as compared to just driving the front onto ramps. Maybe if the car is parked flat no oil may get trapped in the upper oil pan, but from my results I suspect that if I raise the front before shutting off the engine, some oil is getting trapped there.

Eh, you're forgetting about the quart of dirty black oil trapped in the oil cooler & lines. 30 miles of light driving will keep the oil clean. Now go out and romp on it, drive it hard, and get the oil cooler t-stat to open & mix in that last quart of oil oil. Your clear oil will turn black instantly. The amount of soot needed to make all the oil appear black is amazinly small, a few tenths of a percent I believe.

Regards,

I think magnetic drain plugs or a magnet on the side of the oil pan or a magnetic dipstick tube are a good thing....

Dave, I'm not forgetting about the oil in the cooler. Read my previous posts in this thread. Today, after having driven 55 miles since the oil change, I checked the oil again and it's still clear with only a slight hint of opacity at the bottom of the dipstick. It's so clear that I have to tilt the dipstick around under a light to see where the line is. This was 55 miles of mostly freeway driving at 70 mph, with about 8 miles total of uphill freeway driving during which my coolant temp got close to 100C. Do you need a picture of my dipstick or are you still skeptical?

My take on the appearnce of oil after an oil change is that it really doesn't matter much if the oil is supper clean or still little bit dark.
What is important here is that you have changed oil and filter every 3000 miles.

If I want to sell my car, I may consider doing a good thorough oil change so as to impress the potenial buyer.


David

______________
1985 300D Turbo

Hmm, if the oil t-stat has indeed opened and it's clear even with the oil cooler in the loop, that's impressive. But the oil t-stat opens at a higher temperature than you'd think - not related to coolant temp. Only way to make sure is to feel the oil cooler & lines, they will be HOT when the t-stat has opened after a hard drive. I experimented with this once and was surprised at the results.

Of course MB designed the system so that this flushing isn't necessary, the leftover old oil is OK, but the concept sounds neat. Would cost a small fortune to flush with synthetic, which is about all that's in my system for the last 15-50kmi (depending on which car). :D :D There's little (if any) functional benefit to all of this, but as mentioned, it could be a plus while selling a car! :cool:


best regards,

I thought the oil was supposed to be black so that it’s easier to see the level on the dipstick. Can’t stand checking my oil in the gassers when it is hard to tell if there is anything on the dipstick.

Seriously, the “black” is so diluted, I don’t worry about it. It’s refreshing the additive package in the oil that I’m after.

Although I’ll admit I wish I had the persistence for perfection that DieselAddict has.

Dave, I'm quite sure my oil cooler thermostat opened. Although I didn't touch it yesterday, I've touched it at other times after the same kind of driving and it was hot.

You guys might be right that there isn't a significant benefit to having the oil totally clear, especially if you use diesel-rated oil, but I do think there is at least a small benefit. The soot can't be good for anything, and as far as I'm concerned, it doesn't need to be there!

By the way, I have about 7000 miles on my car since I bought it and have done 6 oil changes, all of them with the flushing method I described, but only during the last one did I raise the rear and finally got rid of all the soot, though according to Larry that doesn't appear to be necessary and it appears all I needed to do was avoid driving the front onto ramps. Yes, I persisted until the soot was gone, and now I'm tired of doing oil changes on this car. Going back to 3000 mile intervals...