ker

I have a 99 with 99k miles. I would like to get some input from this forum on the advisability of using a "high mileage" oil such as Castrol GTX High-Mileage oil. Is there any experience on this in this forum that could be shared? Thanks.

A-series

If your engine is using oil, and you think it's b/c of the seals (normally valve seals) letting oil past into the combustion chamber - not mechanical wear or an external leak - a high-mileage oil may help as they condition the seals. However, because they may swell the seals slightly, it would be preferable (in my opinion) to start by adding a quart of the high-mileage stuff along with what you'd normally use at the time of oil change. If that's enough to stop oil use, you can just continue like that. If not, you could try increasing how much high-mileage you use at the change up to %100.
You could just switch straight to all high-mileage, it isn't going to jack up the engine, but if you decided to switch back to only regular after doing that, it might use a bit more oil than before.

If your engine doesn't use oil, or you want to try high-mileage oil mainly to clean out the engine, I'd say skip it. If the engine is fine as-is, despite high miles, there's no need to switch oils.
If you want to clean out a dirty engine, there are other products that you can add shortly before you change the oil (although I'd advise against any sort of "5min. flush" type products) that will clean out more and that way you don't drive for as many miles on dirty oil.

AcuraFanatic

At almost 100K, any "damage" that has been caused by dino oils has already been done. Any beneift that will fall within wear specs of the rings may or may not be beneficial, but it can't hurt either direction.

travchap@embarqmai

I was breifly involved with AMSOIL -- a producer of high quality synthetic oil. They have recommened oil change at 7500-10,000 miles on their product for modern cars. The second best rated oil for lubrication effectiveness per their chart is Pennzoil Platinum at half the cost of AMSOIL. It is also marketed as a high mileage change interval oil. I dont buy the argument that---"oil is oil'.
Do you think top Nascar or F-1 teams get their oil at Walmart??

AcuraTL

No, but do you drive your car as hard as F-1 or Nascar drivers?

mrbkkt1

as much as i agree w/ you to a point, there is a point more toward the middle and lower end of the spectrum where oil is oil.
I use mobile 1 synthetic, and sometimes, the mobile 1 high milage, and truck SUV if they don't have the regular stuff. I've noticed no difference.