[skyship007]

Originally Posted by RoyMacDonald

The extra fuel is injected into the cylinder head. If the fuel is not metered correctly some can end up getting past the scraper ring. Volvo changed the metering and monitoring and the scraper rings some years ago so it's not an issue nowadays unless the engine has a fault.

Increasing the tension on the rings does result in increased wear of both the ring and cylinder.

If you inject extra fuel into the cylinder head some of it will get past the rings and valve guides into the oil. Normal diesel evapourates from hot engine oil, BUT the Bio content does not, so it accumulates and is real bad news in terms of thinning the oil and interferring with the action of the anti wear additives.

When the engine block and injector tips are in perfect condition the amount of fuel in the oil might be less than the 2% listed by an oil analysis lab for a warning flag, but in many cases of older cars or those doing a lot of short trips the amount of fuel will be about that limit, particularly if the injectors are gummed up from using supermarket fuel.

The solution: Cut the oil change interval to half the Max recommended (No need to change the oil filter until max interval) and use a direct feed injection cleaner like Liqui Moly Diesel Purge to fill up the fuel filter housing when the element is changed. A can of a major brand diesel fuel additive every OCI will also work to some extent.

Volvo list 0w30 as the oil spec for newer engines, BUT if your engine is worn or subject to fuel contamination, increase it to an 0 or 5w40 full synthetic.