W208 CLK - Service interval - semi-synthetic oil

[wemorgan]

Last month I had my W208 CLK320 serviced. Semi synthetic oil was used (if I had know I would have requested fully synthetic). The service interval was reset to 10,000 miles. But despite doing mostly long journeys the interval to next service is falling. I would have expected with my types of journeys for the interval to rise initially.

Can the car be on the variable service interval with semi synthetic oil?
If so, can I reset the service interval to be variable?

Thanks.

 

[verytalldave]

I wouldnt use a garage that put semi synth in a modern Mercedes. I would give them a wide berth.
I thought Mercedes specified only fully synthetic to be used.

 

[Matt32AMG]

Last month I had my W208 CLK320 serviced. Semi synthetic oil was used (if I had know I would have requested fully synthetic). The service interval was reset to 10,000 miles. But despite doing mostly long journeys the interval to next service is falling. I would have expected with my types of journeys for the interval to rise initially.

Can the car be on the variable service interval with semi synthetic oil?
If so, can I reset the service interval to be variable?

Thanks.

Was your car serviced by MB or a MB speacialist? As I would've thought either, (and I may be wrong here), would've used Mobile1 Fully synthetic oil. That's all that's ever used in my engine when it's been serviced.

 

[wemorgan]

I must admit I was a bit dissapointed to find that semi synthetic oil had been used. But the garage was a recommended MB specialist. Next time I'll know to supply my own oil.

Any ideas on the variable service interval?

 

[verytalldave]

I would be tempted to go back and demand a refill with fully synthetic to comply with MB recommendations.
I am pretty sure MB stipulate the use of FS oil.

Whichever way, I would not go back there.

 

[LeighW]

My CLK reset at 10000 after my last service, it never rose above that, but the variable system is definitely working. It was down to 2500 miles (approx) when I checked the oil a while ago, and after adding half a litre as instructed, it increased over the next few days to 3200 miles. Which was nice.

Edit to add that the oil was Mobil 1.

 

[wemorgan]

I'll read my handbook this evening and see what oil it recommends then give the garage a call. The car is 10 years old so I would not be too surprised if originally semi-synthetic oil was standard, but regardless I feel fully synthetic oil should have been used.

I vaguely recall reading somewhere that engines designed for semi synthetic oil should not use fully synthetic oil since the cleaning agents can break down the old deposits around seals, which then cause leaks. IS there any truth in this or am I talking rubbish?

 

[Shude]

My car has only been serviced by stealerships with the exception of an oil change by 124works and it's been semi-synthetic every time (not sure what Ian used) but last time my car was serviced by MB I was asked if whether I wanted fully or semi and I asked for fully.

 

[cookci]

I'll read my handbook this evening and see what oil it recommends then give the garage a call. The car is 10 years old so I would not be too surprised if originally semi-synthetic oil was standard, but regardless I feel fully synthetic oil should have been used.

I vaguely recall reading somewhere that engines designed for semi synthetic oil should not use fully synthetic oil since the cleaning agents can break down the old deposits around seals, which then cause leaks. IS there any truth in this or am I talking rubbish?

old high milleage engines that have run on nothing but mineral can start to leak if flush treatments or fully synthetic oils are used


Mineral oil dries out seals in the engine however the deposits left by the oil "reseal" the engine... When 100% clean the engine can start to leak.

synthetic based oils help keep the seals in good condition

 

[grober]

I would be looking at an oil change at 6,000 miles with a semisynthetic to be on the safe side.