C250td OIL CHANGE

gareth805

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Hello,

I have just picked up a mint 98 C250. I just got the car its first service and thought I would check the oil level afterwards (2 days later) to my surprise the dipstick is coming up with the oil looking 'old' and black. My concern is did the dealership screw me and not change the oil or is this normal for a diesel car. My experience with petrol is the oil looks pretty fresh for a quite a few weeks after being changed.

Thanks for any feedback on this.

Gareth
 

pascal

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I would certainly go back to them. Even in a diesel, it should not look old and black, even if they suck it out rather than a full drain.

BTW Gareth, welcome to the forums,
Pascal
 

nicky

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gareth805 said:
Hello,

I have just picked up a mint 98 C250. I just got the car its first service and thought I would check the oil level afterwards (2 days later) to my surprise the dipstick is coming up with the oil looking 'old' and black. My concern is did the dealership screw me and not change the oil or is this normal for a diesel car. My experience with petrol is the oil looks pretty fresh for a quite a few weeks after being changed.

Thanks for any feedback on this.

Gareth

A diesel engine will always make the oil black when it has been run for a short time,this is quite normal..........
 

c250 turbo diesel

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Test for diesel engine oil

I used to run heavey plant for years, boring yes ! but a good test for checking wether a diesel engine oil is old or not, "as the man said it blackens quick" What you do is pull the dipstick wipe it on your fingers, wipe it off with your other hand, if it leaves your finger stained, the oil needs changing, if it wipes off with no stain, it is OK, BELIEVE ME IT WORKS, TRY IT ! Roy
 

JimMac

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Oil Analysis

Hello all, long rambling reply, sorry.

If I remember my college days correctly :-? , Diesel engine oil is complex stuff. Not knowing what mileage yours has done, black oil straight after a service (especially as the car is new to you) would probably indicate that the garage have used an oil that is of a higher rating or quality than what was in it previously. Levels of detergents, dispersents and other additives will vary greatly from one drum to another and so your engine has probably had a bit of a shock because this new oil has been added and given its insides a thorough spring clean. The detergents take the carbon off the internal surfaces usually matched at a rate at which the engine puts the carbon into the lube oil (some of the carbon is where the oil can't stand the heat) the dispersents then lock all the carbon in suspension (rather than it all sinking to the bottom and blocking things up) This is why you shouldn't use Diesel oil in a petrol car as they rely on these carbon build ups to finish off the sealing that piston rings and valve guide seals don't manage. The 250 engine is relatively basic compared to the ultra high performance diesels that most manufacturers build now and so it would stand most oils supplied in most countries so use of a basic oil previously shouldn't have done too much harm. You will probably find that since the oil change you will have some oil consumption as the engine looses some of the carbon that has sealed things up in the past. This is fine and stick to the MB guide on this e.g. 1 litre per 1000km's on my petrol motor.

But if you still have your doubts, there is one definate way to check things out without you falling out with your garage or getting too dirty.

As Roy will remember from his plant days, engines, transmissions etc on heavy plant are usually fixed before they fail and this is done by analysing what state the components are in without having to strip them down. Sounds great and is easy and cost effective. This is all done by analysing the oil from any compartment (some even analyse coolant) with the oil being checked for levels of wear metals, contaminants, coolant, carbon etc etc. Ideally the sampling is done over a period so a history of wear rates can be picked up. I have used it with used motors that I have been dubious about in the past and it gives you a great snapshot.

It costs between £5 and £10 (all Plant dealer depots will do you a cash sale) for a sample bottle (last time I looked) which includes reply paid postage and a sucker to draw the oil into the bottle is also a recommended purchase. This service is offered by all the large plant firms e.g. Cat, JCB, Volvo, Case, Komatsu etc and is done by either Finning's (Cat dealer) own lab in Cannock or by Robertson Research in Wales (JCB, Volvo, Case, Komatsu) they also publish the results for you to view on the web. For more info I have included the following web links. Highly recommended to keen DIY mechanics or garages as an added benefit to owners.

http://www.finning.co.uk/services/support/sos/
http://www.robresint.co.uk/default.asp?section=LS

p.s. used diesel oil in nasty stuff due to high carbon and detergents that dry out your skin so avoid rubbing it on your fingers and wash hands before nipping to the loo, dermatitis can affect even the most sensitive of areas (so I am told)

Regards,
 

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