Thanks for that link, was very informative.
My wife uses the car mainly to and fro work so car sees mostly short journeys and never really thrashed, which will do it some good.
Are there any vw specialists who offer the walnut blasting service? I've seen now on a few bmw/mini forums, specialists who offer the service I may try one of them.
Short journeys don't help these engines and can be considered arduous conditions. Cylinder temps need to get higher than that which might be normal for some to assist in keeping things clean. In these engines anything above 3k rpm for 15mins+` brings about a marked increase in combustion chamber temperature (&EGT's) and a sort of cleaning cycle. It won't get rid of everything but it helps.
I drive 5.5 miles to work and by the time I get there my engine oil is only just at the same temp as the coolant. Because of this and the fact that I do 2/3 track days a year I do two oil changes a year. Ironically not
thrashing may be working against you here, especially if the same driving habits persist after cleaning.
I believe that there are number of other factors affecting this and these are: extended service intervals, engine oils which could be better (consider an Ester based synthetic of the specified grade
http://chemlube-malaysia.blogspot.co.uk/2012/11/the-benefit-of-ester-based-synthetic-oil.html), cheaper fuel that doesn't assist in cleaning or burn as cleanly (V Power Nitro scores well here) and an engine not being properly used. My personal coice of oil is this:
http://www.opieoils.co.uk/p-1146-silkolene-pro-s-5w-40-ester-synthetic-oil-for-high-performance-engines.aspxAll of this simply an opinion based on what I've researched and learnt through talking to my specialist.
Catch tanks may or may not assist in this matter, the jury is out on this one. I have one but I wouldn't say it's a silver bullet, but with other measures taken it may contribute to keeping things cleaner for longer. Where these fit in the intake system isn't the only engine breathing path that contributes to getting things mucky. Having an engine on boost changes things in this respect. A vehicle driven with low boost/revs may benefit from one more than one that spends more time on high boost, especially during the winter months.
It was explained to me that these engines also have overlapping cam timing which can assist in 'baking in place' these deposits.
Addressing these points won't miraculously transform it into a spotlessly clean engine but I believe it will help as some engines with similar mileages can be very different from one another for no apparent reason other than owner/driver imposed variables.
My specialist once told me that he sees some engines which are very much cleaner than others at similar mileages. Given modern manufacturing techniques and quality control the biggest variable in a cars life is the owner/driver.
