But does it meet the VW spec? How would a semi-synth handle the heat of a turbo's bearings? Turbos put great stress on an engine's oil. I'd rather do 15k on the right oil than 8k using oil that can't handle the stress of a turbo application.

(For all I know, semi-synth IS the VW spec, I'm just saying that it surprises me they would spec semi-synth in an engine with a turbo!)

I don't think it has anything to do with the turbo so much as the mileage you expect the oil to survive for. If the engine wasn't capable of having fixed interval servicing they wouldn't offer it as an option. However, if when I go to Clarion they say the wouldn't offer semi synthetic as a low annual mileage option on this engine, I'd go with their advice. I have found them very straight and very knowledgeable.

I don't think it has anything to do with the turbo so much as the mileage you expect the oil to survive for. If the engine wasn't capable of having fixed interval servicing they wouldn't offer it as an option. However, if when I go to Clarion they say the wouldn't offer semi synthetic as a low annual mileage option on this engine, I'd go with their advice. I have found them very straight and very knowledgeable.

My interest here isn't so much the fixed/variable side of things, it's the fact you say you will use semi-synth oil, rather than 507.00 or 506.00 or whatever VW spec is right for your engine.

It could be that for your engine (turbo petrol), the correct VW spec oil is in fact a semi-synth (for fixed intervals servicing). But if it isn't, I personally wouldn't put semi-synth into an engine that is supposed to use fully-synth, especially an engine fitted with a turbo. Remember, turbo'd engines put far greater strain on oil than NA engines, due to the temperatures of the turbo bearings. Normal oil can get cooked, but good fully-synth won't.

What oil is your car supposed to use on fixed interval servicing? If it's a fully synth, I wouldn't go near semi-synth with a barge pole if it were my engine, whatever a dealer or garage tell me. From my (disclaimer: it's a long time since I did my oil research, although I did go to some length to know about it) memory, there is a big difference between semi-synth and fully-synth, semi-synth probably shouldn't be called "synthetic" at all, it's made with a completely different process (hydrocracking, I think it's called). It's just a nasty marketing term. Semi-synth is just "normal" oil that's been very highly refined. Fully-synth is quite different.

Don't assume that a garage or dealership is an expert when it comes to oil. Oil is a very complicated subject, and there are many myths out there when it comes to oil. Follow the VW spec, if you want to be confident that your looking after your engine.

just put VW approved stuff in, that way if it fails you can tell the garage you have used exactly what was recommended for your motor thats been approved.

just put VW approved stuff in, that way if it fails you can tell the garage you have used exactly what was recommended for your motor thats been approved.

I believe their stuff is 5W-30 meeting VW 505

I believe their stuff is 5W-30 meeting VW 505

Which should be fine for fixed.

Same exact thing happened to me this week. Car in for 3rd variable service - i supplied the oil. After reading this post I thought I would check - 9300 miles 371 days till next service. Phoned the dealer - lots of apologies and offering to reset it. Please check before you leave the dealer! I now have a 60 mile round trip to get it corrected