Oil. Synthetic vs. Semi-synthetic

[4450]

Made the comment yesterday in a converstation that I run synthetic oil in my diesel pickup and a couple of my gasoline vehicles just because I can run it longer and have less oil changes to do. The fellow I was talking to said I should switch to semi-synthetic because it will perform just as well and cost half as much. Any opinions? I change oil every 5000 miles with the synthetic.

[PERCY]

4450, when you've got such good s#it that you don't have to add oil for 5,000 miles, I ain't got no opinion thats usefull!!! LOL

[drdiederich]

I think, first and foremost, read the owner's manual and see how often they say you should change on regular oil... My car is 7000, and I have been doing that since I bought the car, new, in 2000 with no problems. On the other hand, my brother likes semi-synthetic for his van and changes it every 7000 (or more honestly 8000 by the time he gets around to it) and the manual says 5000. If it weren't for changing oil every 10,000+ miles I would make the switch but I don't think I would ever remember to do it would be so long between changes!

[4450]

I think, first and foremost, read the owner's manual and see how often they say you should change on regular oil... My car is 7000, and I have been doing that since I bought the car, new, in 2000 with no problems. On the other hand, my brother likes semi-synthetic for his van and changes it every 7000 (or more honestly 8000 by the time he gets around to it) and the manual says 5000. If it weren't for changing oil every 10,000+ miles I would make the switch but I don't think I would ever remember to do it would be so long between changes!

I'm from the old school, dr. First of all, in the old school you never read the owners manual to see what it recommends other than the specified viscosity, lol. Second, in the old school it was every 3000 miles. This fellow I was talking to pointed out how even conventional motor oils of today are better than 30 years ago.

My stuff isn't that new Percy. My vechicles usually have 75,000 or more miles when I buy them and then I hope for the best. But engine wise, I've had pretty good luck. Our old taurus stationwagon that was the good car, then the Mrs. work car, than the daughters school car, and is now just a spare that we should get rid of has 259,000 and still only uses a quart to 3000 miles. Don't use synthetic in that one. Penszoil.

[drdiederich]

I'm from the old school, dr. First of all, in the old school you never read the owners manual to see what it recommends other than the specified viscosity, lol. Second, in the old school it was every 3000 miles. This fellow I was talking to pointed out how even conventional motor oils of today are better than 30 years ago.

Normally I'm totally with you on the owners manual thing in general... I can't say I'm big on them, though they can come in handy from time to time...

Yeah, lots of people still live by the 3000 thing, I'd just as soon know, so I don't waste my time and money (though the time is more important since I don't really enjoy it, especially in winter since I don't have a heated shop) but I suppose it doesn't hurt to change it. Once someone pointed it out to me I now make sure so save myself the job...

He brings up a good point about oil today being better than it was in the past. That's what one of my engineering buddies was told me that used to work for Oshkosh truck. He used to like to buy his personal cars/trucks old and cheap, so he was complaining that he had to add oil in which wasn't cool because the oil would last so much longer if he could keep it in... so he wanted oil as cheap as possible.

[SteigerGreen]

We are running Amsoil synthetic oil with Amsoil Ea filters in my mom's and sister's cars. It is good for 25K miles or one year, we change it once a year and it has been working great. On other vehicles they would get in the 7-8K mile range by the time we got the oil changed, which is too many with conv. oil IMO. With the Amsoil we don't have to worry about them. I'm not sure what the service interval is for diesels using this oil but I'm sure it would be longer and offer better protection than conventional oil.........Steiger