[Huskymaniac]

Originally Posted by dcarrb

I remember Dad relating something akin to this many, many years ago, saying that a mechanic friend in a fleet maintenance shop insisted all they did was replace filters and top-off the crankcase.

Don't think I'd go that far.

Hard to see how opting for a larger filter could be a bad thing, unless oil flow and/or pressure are adversely affected. As to oil brands and types, all of these "condition-specific" products on the shelf have way more to do with marketing than science. Floor polish or dessert topping? Often it's just a matter of packaging and spin.

dcb

I don't think there are any miracle cures out there but there are too many cases where they seem to have a positive impact for it to be totally smoke and mirrors. High Mileage oils have clearly shown to slow leaks and other effects seen in higher mileage engines. And if you see the oil analysis, you can clearly see there is a difference between, say, M1 and M1 high mileage. The high mileage oil is thicker, has higher TBN and higher HTHS numbers.

If you read enough forums you will find claims that every oil out there has "destroyed" someone's engine. Someone mentioned Castrol. I have read a lot of bad claims about Castrol, for example. I find the claims dubious at best but it is possible that each engine and/or application prefers certain oil characteristics. High revving engines want thicker oils with higher HTHS. Engines with tight passages want thinner oils. Older, worn engines want thicker oils. People going a long time between oil changes need a high TBN. Engines that are sensitive to leaching metals out of bearing want oils with acid neutralizing additives. These things really do matter but knowing what your engine needs and finding the "perfect" oil is quite difficult.