Oil and Filter change

[paul73mt]

So my cars just had its b service at MB last week all fine and not even a phone call to say it needs this and that. So currently i drop the oil and change the filter every 6 months. Now due to my car now passing 140000miles do you think it could be worth it to change the oil n filter say every 4 months or so or just keep it at every 6 months???

 

[grober]

Depends on mileage travelled and running conditions 4 months seems overkill to be honest unless the car is subject to what Mercedes term " arduous conditions" I suspect you might benefit more from changing some of the other fluids/filters on a more regular basis [ not 4monthly!] such as the autogearbox fluid/filter rear differential fluid air intake filter etc . Engineering bods will tell you the only real way to judge whether an oil needs changed is to subject an oil sample for wear analysis by looking for trace elements of bearing material by spectroscopy! That's how the offshore oil platform guys used to do it once upon a time!

 

[paul73mt]

cars doing around the 16,000 miles a year and prob over 90% motorways. was still going to keep the serving up with MB, I believe the gearbox oil and filter was done at 37K @ MB and then at around 85/90K @ Wayne Gates so will get that done next service, But never thought about the diff oil.I will have a look into that

 

[190]

No earthly need to do it every 4 months with that annual mileage and type of use.

 

[paul73mt]

No earthly need to do it every 4 months with that annual mileage and type of use.

It was only a question thought dropping the oil more often would help, But i suppose it not really 'working' just sitting on the motorway. Have been looking at the service schedule with MB and it appears the diff oil is never changed. So that's one for the list and also cant see the gearbox oil n filter change so that's another one

 

[toteimerced]

The more the merrier imo, I like to do mine every 4K, oil is the life blood of your engine, the fresher the better, the guy with the P1800 which has done 1.8 million miles, puts it down to very regular and often oil and filter changes.

 

[markjay]

The more the merrier imo, I like to do mine every 4K, oil is the life blood of your engine, the fresher the better, the guy with the P1800 which has done 1.8 million miles, puts it down to very regular and often oil and filter changes.

With £16k miles per year.... it would take over a hundred years to get to 1.8m miles.

So if changing the oil every 6 months means the engine can live up to (say) 300k miles, but with an oil change every 4 months it will live to (say) 400k miles, the issue becomes academic.

The reality is that the days of one or more engine rebuilds due to wear during the life of the car are long gone.

With rare exceptions, engines today easily outlive their cars.

And when engine failure does occur, it will be due to component failure and not due to normal wear.

So changing engine oil at the manufacturer's specified time and mileage intervals is nore than enough for the majority of cars.

Unless, of course, you run the car as an airport shuttle minicab around the clock with 3 drivers. But this is about the only case where normal engine wear might dictate a rebuilt before the car expires naturally.

 

[190]

Oil experts have found that wear rates are initially higher with new oil as the high detergent level strips off the antiwear layer which then has to be built back up again. That would suggest oil changes more often than necessary isn't merrier. It may sound totally non intuitive but it's based on oil analysis and science.

Our biggest pre-conception with oil is thinking it has to be spotlessly clean to lubricate properly. The reality is that dark oil is normal and just an indication that the detergents in the oil are doing their job.

 

[toteimerced]

Check out fifth gear ten k oil analysts, if you can find it on line somewhere, it’s a real eye opener, it included 0-100mph runs, before and after oil change.

 

[alabbasi]

Change every 5000 miles with synthetic and a good quality filter. It's cheap insurance.

 

[grober]

PERHAPS THIS IS THE FIFTH GEAR PIECE?

To view this content we will need your consent to set third party cookies.
For more detailed information, see our cookies page.

Accept third party cookies

 

[Yugguy]

With an electric pump and a top mounted filter oil changes are easy. I do mine every 4.5k as diesel oil gets sooty quickly. (Yes I know that this is what it is designed to do.)

 

[grober]

dup

 

[190]

I do mine at 4000 miles but that's annually not 3 times a year.

The fifth gear piece is very pretty pseudo science. If the used oil was lower in viscosity then in the absence of any other mechanism (non were stated) the car sould have gone faster not slower. Not by much though. Dynamometer tests have shown increased power with reduction in oil viscosity but we are talking small percentages and not enough to make 0.7 secs difference on a 0 to 100 time.

The fact that the oil viscosity had dropped is typical and indicates the oil wasn't overdue for a change. The viscosity quoted was still within the SAE J 300 band for a 5W40 or 0W40 oil i.e. it was still in grade. Used oil initially drops in viscosity either due to fuel dilution or break down of the viscosity index improvers. It then rises again above it's original viscosity due to oxidation and ultimately turns to sludge. When it starts rising again is the time to change it.

Viscosity reduction due to fuel dilution has become more of an issue for modern direct injection engines and for that reason if a vehicle is permitted to use say either 5W30 or 5W40 I'd go for the 5W40 every time.

 

[grober]

I do mine at 4000 miles but that's annually not 3 times a year.

The fifth gear piece is very pretty pseudo science. If the used oil was lower in viscosity then in the absence of any other mechanism (non were stated) the car sould have gone faster not slower. Not by much though. Dynamometer tests have shown increased power with reduction in oil viscosity but we are talking small percentages and not enough to make 0.7 secs difference on a 0 to 100 time.

The fact that the oil viscosity had dropped is typical and indicates the oil wasn't overdue for a change. The viscosity quoted was still within the SAE J 300 band for a 5W40 or 0W40 oil i.e. it was still in grade. Used oil initially drops in viscosity either due to fuel dilution or break down of the viscosity index improvers. It then rises again above it's original viscosity due to oxidation and ultimately turns to sludge. When it starts rising again is the time to change it.

Viscosity reduction due to fuel dilution has become more of an issue for modern direct injection engines and for that reason if a vehicle is permitted to use say either 5W30 or 5W40 I'd go for the 5W40 every time.

Agreed what was reasuring from that piece was that despite 10,000 miles the oil had basically remained in grade and was doing its job. What might have been interesting would have been to establish a contamination/degradation profile/curve to monitor how the oil changed over time- was it linear with time or was there a rapid initial contamination rise [ from old engine oil left in the galleries?] followed by a slower rise with time--- this could only be answered by sampling the oil at regular intervals over the 10K [ 1,000 MILE INTERVALS say?]
As usual however it served to remind me of one of the primary functions of engine oil-- that of a first line engine coolant . This suggested to me that any mercedes owners suffering a main coolant failure/overheating "incident " might be well advised [ in addition to rectifying any cooling system problem/leak] to change their engine oil as a precaution??

 

[markjay]

I do mine at 4000 miles but that's annually not 3 times a year.

The fifth gear piece is very pretty pseudo science. If the used oil was lower in viscosity then in the absence of any other mechanism (non were stated) the car sould have gone faster not slower. Not by much though. Dynamometer tests have shown increased power with reduction in oil viscosity but we are talking small percentages and not enough to make 0.7 secs difference on a 0 to 100 time.

The fact that the oil viscosity had dropped is typical and indicates the oil wasn't overdue for a change. The viscosity quoted was still within the SAE J 300 band for a 5W40 or 0W40 oil i.e. it was still in grade. Used oil initially drops in viscosity either due to fuel dilution or break down of the viscosity index improvers. It then rises again above it's original viscosity due to oxidation and ultimately turns to sludge. When it starts rising again is the time to change it.

Viscosity reduction due to fuel dilution has become more of an issue for modern direct injection engines and for that reason if a vehicle is permitted to use say either 5W30 or 5W40 I'd go for the 5W40 every time.

I agree, and as much as I find the Fifth Gear video clip enjoyable, it is also quite misleading.

Almost all service items start degrading as soon as you start using them: oil, filters, tyres, brakes, spark plugs, etc.

But as long as the item is still within its design spec, it's fine to use.

You could equally test drive a car with new 8mm tread tyres, and then compare it to (say) 5,000 old tyres with (say) 6mm of tread.

As expected, the brand new 8mm tyres will perform (marginally) better than the 6mm tyres.... shorter stopping distance, faster cornering, better resistance to aquaplaning, that sort of thing.

And then you could argue that tyres sould be replaced every 5,000 miles because at 6mm they perform less well than when new.

There is no end to it... I would say that if you change the oil every 4k miles because it has 'deteriorated' compared to new oil, the same logic dictates that you should also change at the same the air and fuel filters, spark plugs, brakes and tyres (and Battery, and ATF, and coolant, and brake fluid.... etc etc) - because they are all important and they will now perform less well than when new.

Instead, I suggest that you should simply follow the manufacturer's service schedule (covering both fixed inteval items as well as on-condition items), which will see service items replaced before their performance deteriorates below a pre-defined minimum threshold.

 

[190]

By coincidence this same video was posted today on an oil forum where some professional oil formulators are members. The general consensus was quite negative with comments like "multiple technological errors " but the technical description I liked best from a guy who's opinion I would trust is that it was "utter bol***cks"

The whole issue of TV science is interesting. Put someone in a white coat in a laboratory setting and they have instant credibility. The general TV audience will think that the presenter knows what they are about when in fact the only thing they know is how to make entertaining TV. It's about as genuine and scientific as those TV adverts where a "Dentist" is telling you off for not looking after your gums.

 

[Petrol Pete]

cars doing around the 16,000 miles a year and prob over 90% motorways. was still going to keep the serving up with MB, I believe the gearbox oil and filter was done at 37K @ MB and then at around 85/90K @ Wayne Gates so will get that done next service, But never thought about the diff oil.I will have a look into that

I asked my indie to change the diff oil on my C55 AMG, the car had over 100000 miles on it and I had no record of it being done. I thought a car with a decent amount of power and a heat exchanger fitted to the diff as standard might benefit from a change. My indie thought better and said it probably not worth doing ! I overruled him and asked him to do it anyway. Not sure if I wasted my money but it gives me peace of mind.

 

[190]

MB do not define an oil change for the Diffs, manual gearboxes or Kompressor oil. They are filled for life. There is some basis of logic in that approach as the oil doesn't get contaminated except by wear particles and they should normally be captured by the magnetic drain plug. Oil itself doesn't wear out but additives will eventually get consumed. I think these oils should be changed even if it's only once or twice in the typical life of the vehicle.

 

[Yugguy]

I changed my diff oil at 59k. It looked ok but was definitely darker than what went back in. With access to a lift it was quite easy. I might do it again at 110kish if I still have the car.