Fluid Changes-'01 CL500 - PeachParts Mercedes-Benz Forum

Jud Chapin · #1 02-06-2004, 09:10 AM

I'm purchasing an '01 CL500 soon and need info on changing motor oil & filter, and tranny fluid and filter. Anything special I need to know regarding procedure and computer data that needs to be reset. I'm assuming these are things a DIYer can do.

vince · #2 02-06-2004, 11:50 AM

I would ignore the FSS system and lifetime trans fluid schedule.

Change the engine oil and filter every 5,000 miles. Use Mobil 1 0W-40.

Change the transmission oil and filter every 30,000 miles. You must use M-B synthetic fluid in trans and need to buy a dipstick at the dealer. You also need a clip to "reseal" the dipstick tube.

I would do the differential at 30,000 miles also.

Brake fluid flush every 2 years.

I would change the coolant every three years. Use M-B coolant.

You can reset the FSS dash display with instructions in the Owners Manual.

Ali Al-Chalabi · #3 02-06-2004, 01:09 PM

Every 30k miles for the 722.6 tranny is excessive.

Fluid level is dependent on temperature and you cannot get the correct level if you do not know the temperature of the fluid. I do not agree that this tranny is a permanent fill but I would consider every 30k miles unnecessary.

vince · #4 02-06-2004, 02:05 PM

I didn't pull 30,000 miles on the transmission out of the air. I believe the professional techs on this site support that frequency based on what they have seen in the actual service, but if they disagree they can surely correct me.

The work around for the temp/level is to measure the level right after a cold start and record it. Drive the car over a specific route of about 20 miles. Check the level and record it. Drain the fluid making sure to collect it all. Measure the volume. Refill the same amount short a pint or so. Check the level after a cold start. Don't correct unless there is some gross error (which there should not be). Drive the car over the previous route and check the level. Adjust and seal the dipstick tube. Sounds like a lot of work, but it really isn't that bad.

Ali Al-Chalabi · #5 02-06-2004, 03:42 PM

The suggestions on this board are for every 60k miles.

I have an infrared thermometer to monitor trans temp. Driving it to count on it getting to a specific temp is not the most accurate way to do it. With a 20 mile drive and below freezing outside temps, I have seen the tranny barely break 110F.

vince · #6 02-07-2004, 07:57 AM

Ali - After some searching I stand corrected on the transmission fluid change interval - at least with respect to what this forum is recommeding. My info was from a knowledgeable source in MBCA. I stick to my personal recommedation. Even though the fluid is expensive, a changeout is cheap in the overall scheme of things. Just my opinion.

However, I am not a fan of infared units. I'm in the marine industry. We have used infared thermometers for years when trying to confirm readings from various temp sensors. We have used units from Raytek and Fluke. We have come to the conclusion that most of the affordable units are too inaccurate to be of much value. I am not sure why. My guess it is because of outside factors as the basic accuracy is usually acceptable. We only use them for a general check (trending, for example) or where no sensor is fitted. We do have a contractor that performs regular thermography on our switchboards and they use infared cameras, but the cost of their equipment is far too high for our purposes, as it would be for a DIYer for a transmission fluid change. I have a Fluke 61. The only time I used it for a similar proceedure was on a VW Passat. My Fluke was some 30 degreesF different from the reading I got from my VAG-COM program (which reads the transmission temp directly from an internal sensor in the same way the M-B dealer equipment does).

I am confident in the work around procedure. While the exact temp is not checked, the same level is established after service as before at similar temps (cold start and 20 mile drive). The fluid will expand the same amount. The point is to match the dipstick readings you get before and after, not to fill the trans to the 80 degreeC marks if it was not there in the first place. Provided the transmission was at the correct level in the before, it will be after service. Plus, measuring the exact quantity of fluid drained is a confirmation. In my opinion, the idea that the level must be so very, very precise does not dovetail with the fact that the 80 degreeC range on the factory dipstick is 11mm wide.

I'm a bit surprised at the 110 degreesF. After all, the transmission cooler is in the radiator, surrounded by the engine coolant, which should be at around 180 degreesF and, to my knowledge, there is no "thermostat" that bypasses the cooler until a preset temperature. I'm surprised at what appears to be a lot of radiant loss over of couple feet of connecting tubing.

Ali Al-Chalabi · #7 02-07-2004, 10:27 AM

Vince,

Thanks for the info on the inra-red thermometers. I use mine for an estimatioon and I have verified its accuracy of measuring at least liquids with a mechanical thermometer and it seems to match to the coolant temp sensor pretty close. It is supposed to be accurate to +/- 3 degrees F, so I trust it to be in the gerneral region. If you have a source that says it is better to change it every 30k miles then that is fine, I am just stating what the general consensus of the mechanics is around here.

The reason the transmission temperature stays so cold in winter is because the coolant/ATF heat exchanger is built into the radiator on the cold side of the radiator. On my car, as with a lot of other MBs, the radiator is a cross-flow type. It flows from in on the driver's side goes accross the whole radiator, through the ATF cooler on the passenger side and back accross to the driver's side and out back to the engine. This means that after a drive at speed through the 30F air, the temperature of the coolant that the ATF cooler is submerged seems to be no warmer than 50-60F. The radiator at this point is very cold to the touch. There is no thermostat for the ATF so it flows through no matter what. The engine thermostat has a slight regulating effect in that it is further closed when it is cold out and thus there is less quantity of coolant flowing through the cooler and a higher temperature differential between the ATF and coolant so it does not become as cold as the coolant. However, the temp of this coolant is very cold on this part of the radiator and thus cooler trans temps. Tranmission temp seems to be dependent on 3 main factors, road speed, type of driving, and outside air temp affects it as well.

-Cheers