Quote:
Originally Posted by chuckster57
I installed a bypass oil filter on a customers '97 PSD, and about 100 miles later he said it looked as golden as it is out of the bottle.
It wasn't cheap.. would I do it? Probably not.
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Bypass filters are nice, but it takes a lot of oil changes to pay for them. They say a quality synthetic oil that doesn't break down like a dino oil does will last forever..."in theory". IMO, the problem with a bypass filter system is it can give false impressions of oil quality. It filters down to a smaller micron level and will remove a lot of the soot that makes the oil black. In reality, the soot is so small, it doesn't do any damage to the engine anyway. It's not the color that determines if the oil is still good, it is the additives and the ability to clean and control acid build up caused by the combustion process. The main characteristic to be concerned with is the TBN (total base number). As the TBN numbers break down, the oils ability to neutralize corrosive and damaging acids is reduced. An oil can "look" clean, but the TBN number can be at dangerously low levels.
As for synthetic vs dino, synthetic has the advantage mainly in the area of consistent viscosity throughout the life of the oil, whereas a dino based oil will begin to change viscosity characteristics almost immediately. Due to burn off, the oil you drain out after 5-10k miles is much different in viscosity than the oil you put in.
Wow, that really got a lot longer than I intended, sorry.