oil for a high mileage engine?

[daisuke]

Hey guys, I thought I'd ask around in here first about oil before I went out and bought any, I have a few questions in any case:

1) What would be the best oil for an engine with roughly 215K miles on it? I know that I'm not supposed to put sythetic into this thing since it's been running on regular oil for most of the time and I don't want it to start leaking or getting blowback. (the engine is a twin cam aluminum block saturn engine, 95 SL2) I found quite a lineup, among the oils I found readily available were: Castrol GTX and startup, Exxon High Mileage, Havoline, Motorcraft, Quaker State and Valvoline, all these oils are 10W-30. There is currently castrol GTX 10W-40 in there.

I would seem inclined to go for the Valvoline or Exxon oils right now

2)why is it that almost no high mileage oils are Energy Conserving? (the Exxon high mileage is the only one I've found) A guy at napa told me that as long as the oil has the same weight and api rating there shouldn't be any friction difference between the two.

thanks for all your answers in advance,

D

 

[Jelly]

*What would be the best oil for an engine with roughly 215K miles on it?

Just depends...

*I know that I'm not supposed to put sythetic into this thing since it's been running on regular oil for most of the time and I don't want it to start leaking or getting blowback.

Albeit most of the time, you're correct. With such a high-mileage engine that has spent it's life on a mineral PCMO, you'll likely experience some seal issues if you just straight to a group IV/V synthetic lube.

*the engine is a twin cam aluminum block saturn engine, 95 SL2

Based upon the experience of fellow BiTOG member Mkosem, who had a '94 SL1, I'd recommend Mobil Delvac 1300. Should work great in this high-mileage engine.

*why is it that almost no high mileage oils are Energy Conserving? A guy at napa told me that as long as the oil has the same weight and api rating there shouldn't be any friction difference between the two.

Without getting too in depth, high-mileage oils won't achieve "energy conserving" status simply because they are formulated to the thicker end of their respective viscosity spectrum and thus will not achieve energy conserving status.

Remember, two oils can be labeled 10w-30, but the viscosities of each can vary a good deal.