View Full Version : "High Mileage" switch to synthetic?

04-09-11, 07:42 AM
Hey everybody,

We have 60K on my wife's 2000 Catera Base. Some of you may consider that high mileage, some may not.:) We bought the car at 50K less than a year ago. Unsure what oil was used in it by the previous owner, though we do have one receipt for some other work that indicated a change with high mileage dino oil. Anyway, I've had two oil changes done since we got it, both with whatever crap the lube place puts in. Before the last change, they sold me on flushing out the engine with "oil system cleaner", in which case I believe I was ripped off but no harm done, except to my wallet.

Anyhow, having lived in apartments for some time, I now have my own house and my own driveway, so I'm going back to changing my own oil. I was considering going to Mobil 1 high mileage, but have heard warnings about switching to synthetic at high miles, because (a)the synthetic oil can clean out gunk left by the dino oil and, potentially, passages could get blocked with chunks of the stuff, and (b)the smaller molecules of the synthetic oil could seep out of gasket leaks small enough to not be a problem with the larger molecules of the dino oil.

My initial thought is to go for it. As far as (a), I'm thinking that anything nasty would have come off during that flush I was sold on. As (b) goes, I'm thinking that first, the conditioners in the "high mileage" version of M1 would help, and second, I could always switch back. So those are my thoughts, but I was wondering what you all would have to say about it.

BTW, I'm planning on sticking with 5K intervals, as this car is mostly used for short trips.

AL Cool Dates
04-09-11, 11:23 AM
I was thinking of starting the very same thread, except that my car has a 151,000 miles on the clock and the last flush I had cleaned out a lot of gunk (previous owner must have not been too good with the oil changes). I'm wondering the same thing with synthetic too about my car being too old for it.

04-09-11, 04:42 PM
I started mine at around 60K then switched back to mineral around 90K because I started to get blue smoke on start up.. but at around 100k went back to Synthetic and to this day I run 10W-40 almost year round on my car.

I have 160K on the clock as well, motor is a bit worn out by now so the extra thickness does well for noises and to keep it from leaking.