I have an 850 turbo with about 225000 miles which doesn't leak or use much oil. I've been using regular oil but my mechanic keeps telling me to switch to synthetic. I heard that switching in a hi mileage engine will cause leaks. Any advice?
IMO synthetic oil is a very good idea with turbos. If you are worried about leaks, Valvoline markets a Synthetic MaxLife oil which is supposed to include seal conditioners to minimize leaks.
Personnally, as long as you dont drive it very hard 100% or tow heavy loads in high ambient temps, and use a good spec mineral oil of the correct viscosity, changed at around 5k intervals, then I would NOT switch to Synthetic.
The main advantage of synthetic is that it will withstand higher temperatures without carbonising- i.e in the turbo. As long as you cool off the turbo after driving on boost, mineral will be fine.
You will prbably cause more problems such as leaks and wash any deposits into the sump which could block the pickup strainer.
I always wonder why oil changes are done so frequently in the US, even on European cars. I'm driving currently a new V70 D5 (185 hp) and before I had a V70 T5 (260hp). In Europe oil changes are done every
20'000 to 30'000 km (13'000 to 20'000 miles) or after 24 months which ever comes first. But along with the engine oil the filter is always changed. Shorter intervals are only recommended in very sandy or dusty environments.
The other thing is the frequent statement in this NG that the switch from regular mineral based engine oil to fully synthetic engine oil on high mileage cars is producing oil leakage. If that were the case the engine has *IMHO* a major structural defect. Molecule chains of fully synthetic oils remain much more stable which results "thicker" oil when hot. From the standpoint of physical properties of the oil qualities there is no reason not to switch to synthetic oil.
It's not just the USA where oil changes are recommended at 5k miles intervals. Many respected commentators here in the UK (e.g. The Daily Telegraph's motoring writer "Honest John" ) have long espoused ignoring the manufacturers' extended limits and changing the oil every 5k miles (or 6 monthly if sooner). A local garage that services Mitsubishi Colts for a driving school had horrendous camshaft problems when Mitsubishi extended the oil change interval from 6k to12k a few years ago. The driving school removed the problems when they reverted to 6k oil change intervals.
I don't know how many miles your V70s have covered, but my 850 has managed 215k miles with no major component replacements, and has had the more frequent oil & filter changes. John Morris, Cambs UK
John, that is not my personal opinion. The manufacturer Volvo decided that it is appropriate for the European markets. So do other manufacturers like Daimler Benz, BMW and others.
Before the V70 s I also drove several 850s. The last one was a 850 T5 (225 hp). The colour and the consistency of the engine oil led to the conclusion to stick to the manufactureres advice/recommendations.
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