# Switching from conventional to synthetic



## mark.now (May 7, 2009)

Hi,
I've recently acquired a 2004 Passat GLS 1.8t 5spd wagon - love it!
76,000kms on the clock.
Previous owner used conventional oil only. I had the first change done 3 days after buying. Used Castrol Syntec 5W-30. Now I'm finding out to my dismay that 5W-40 is recommended, 5W-30 only in a pinch.
More importantly - should I switch to synthetic 5W-40? What's going to happen to the seals, etc, that have all been seated and conditioned on conventional oil?
I'm new to this turbo motor thing but an hearing a lot that synthetic is the only way to go. I want this car to last a long time.
Comments?


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## raakpatel (May 28, 2009)

*Re: Switching from conventional to synthetic (mark.now)*

5W30 is ok. I own a shop and most European cars give you several choices but 5w/30 is about 75% whether its a VW, Audi or another european car. I have 2001 A4 and run shell 5w/30 Synthetic. I have had it tested after a few times and it came back fine. I can run anything I want since we stock it all including Mobil 1. Also switching to synthetic is ok even if the other owner ran conventional. A little trick if you want to clean out the inside of your engine is to put a cup of traditional tranny fluid for about a few days and then change your oil. The detergents in the tranny fluid will clean up any gunk build up and usually will not harm the engine.


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## tjl (Mar 24, 2001)

*Re: Switching from conventional to synthetic (mark.now)*


_Quote, originally posted by *mark.now* »_I've recently acquired a 2004 Passat GLS 1.8t 5spd wagon - love it!
76,000kms on the clock.
Previous owner used conventional oil only.

Keep a close eye on it for any signs of oil sludge (e.g. low oil pressure due to sludge clogging up oil lines or oil pump). Those engines were particularly vulnerable to oil sludge if conventional oil was used.


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## GT17V (Aug 7, 2001)

*Re: Switching from conventional to synthetic (mark.now)*


_Quote, originally posted by *mark.now* »_Hi,
I've recently acquired a 2004 Passat GLS 1.8t 5spd wagon - love it!
76,000kms on the clock.
Previous owner used conventional oil only. I had the first change done 3 days after buying. Used Castrol Syntec 5W-30. Now I'm finding out to my dismay that 5W-40 is recommended, 5W-30 only in a pinch.
More importantly - should I switch to synthetic 5W-40? What's going to happen to the seals, etc, that have all been seated and conditioned on conventional oil?
I'm new to this turbo motor thing but an hearing a lot that synthetic is the only way to go. I want this car to last a long time.
Comments?

do the auto-rx treatment to clean the engine with conventional or a Group III oil. Petrol Canada Duron 5w40 is a good oil to use.
then you should be able to proceed with 8000 km oil changes, and make sure you use the larger oil filter VW & Audi specifies since the oil sludge fiasco


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