If you change a 2002 Passat 18 Turbo to synthetic oil will this benefit or hurt the Turbo's life?

You MUST, MUST, MUST use synthetic in you 1.8T. The 1.8T is very prone to oil coking or sludging because exhaust turbos are exposed to very high temperatures (they glow under heavy load!). The oil is circulated through the turbo to lubricate it and cool it. Refined crude lubricants can not stand up to the high temp, break down, and then you are in for some very expensive repairs ($1,500-$8,000). Any lubricant put into a 1.8T has to meet volkswagen spec VW502.00 or VW will not pay for repairs if you have a sludge damage issue, and the only oils on the market in the U.S. that meet that spec are highly refined group III (group III are usually inaccurately called full synthetics) or higher full synthetics, such as group IV and V that are mostly only available in europe. Here is a message board with a lot of good info: http://www.passatworld.com/forums/showthread.php?t=225417 Again, FULL SYNTHETIC ONLY! Not a blend, only full synthetic, no matter what they tell you at Jiffy-lube or the dealership. The best option is to actually buy your own oil at a retailer to make sure that it meets spec, and take it with you to the dealership, because then you know they are not shorting you and using the right fluid and they will only charge you labor. Additionally, synthetics are actually cheaper because they last longer and you can go longer between oil changes, usually at least twice as long, but for a VW the manual specifies intervals of 5,000 miles, so i would not exceed that in case you end up with sludge/coking damage. If you do not comply with the service recommendations you void the sludge warranty, which is 8 years from original purchase and unlimited miles. Also, you will get better overall fuel economy and longer engine life with synthetics because they reduce the friction on internal engine bearings.

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Sure won't hurt and may help. [WRONG!!!]

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Oil does not have much of an effect on the turbo because the turbo just rams the air/gas mixture into the engine. [REALLY WRONG!!!!]

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The turbo uses the engine oil a a lubricant, so it does have an effect. [Correct, but incomplete]

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Because the turbine spins at extremely high speeds and is lubercated by the engine oil, it is very important to the wear and life of this very expensive part. Therefore, oil becomes an even more important issue on a turbocharged motor. They run at extremely high temperatures and good synthectic oils don't break down like regular engine oil at very high temperatures. That is the reason your owners manual calls for synthetic oils with certain specifications. Technically, it doesn't affect the running of the engine, that is if life of the engine is of no concern.

First answer by Clay. Last edit by Titob. Contributor trust: 1 [recommend contributor]. Question popularity: 59 [recommend question]