best conventional oil?

going back to changing my own oil....It's getting too expensive. Back when, Castrol used to be one of the best conventional oils. I've got 2 higher milage engines...70K and 79K..so I don't think i want to switch to synthetic oil at this point.

I'm using Quarker State Higher Mileage oil and it is doing fine.

there are numerous posts about this. Synthetic would be a bad idea unless you have already been using it. Mobil 1 is one of the best off the shelf oils because they use no viscosity enhancers. If you choose other than mobil one, your best bet is to go with a 10w-30 so there is less of a viscoisty range IE: less viscous additives. This site is pretty good at explaining it. http://auto.howstuffworks.com/framed.htm?parent=question164.htm&url=http://www.vtr.org/maintain/oil-overview.html

It's fine to switch to synthetic oil even on an old engine. There are often cheaper synthetic oils that can do a good job in an old engine.

High mileage usually means that you need a little thicker oil.

the problem with switching to synthetic after using regular oil on a high mileage car is that the sludge deposits and buildup of years of broken down polymers amoung other ingredients will get cleaned out by synthetic oil. This is not really good for an engine as one could imagine. You are correct in that he does want a thicker oil for the seals, rings, etc.

the problem with switching to synthetic after using regular oil on a high mileage car is that the sludge deposits and buildup of years of broken down polymers amoung other ingredients will get cleaned out by synthetic oil. This is not really good for an engine as one could imagine. You are correct in that he does want a thicker oil for the seals, rings, etc.
Not true, this is just a tale that is leftover from the early days of synthetics.

Synthetic and regular oil both contains the same cleaning addetives. If the engine is dirty inside both a fresh synthetic or regular oil will losen it up.

go to amsoil.com you will find exactly what you ned and they will reccomend. The problem is that its a bit expensive look into it anyways.

I have heard many people say that switching from syn. to reg. oil or vise versa is bad. Also have heard alot of talk about not switching brands. I don't think it really matters myself. As long as you change your oil regularly the engine will love you. :)

I have heard many people say that switching from syn. to reg. oil or vise versa is bad. Also have heard alot of talk about not switching brands. I don't think it really matters myself. As long as you change your oil regularly the engine will love you. :)
It's all just tales. It's fine to change as you want, as long the oil is suitable for your engine.