1990 4Runner V6 w/ 205,000 miles. Should I switch to synthetic oil?

[Dennis S]

It sat up for almost a year and I started driving it again. I need to change the oil right away. Is this as good time to switch to synthetic? Does anyone have a favorite brand? I'm using 10/30 Castrol now.

[Don Kiyoti]

No. Generally considered a bad idea to put synthetic in a high-mile engine. Stick with the Castrol.

[macphanatic]

At this point, there is no reason to.

[mrbigstuff]

macphanatic wrote:
At this point, there is no reason to.

i agree with this

there are many reasons that car will fail for other reasons beyond the engine. most just end up rusted beyond repair or some electrical problem or some major work paired with an full exhaust replacement, etc. those things are usually more $$ than the car is worth so many people just cut their losses and say good bye.

i'm still driving an early '90s camry with 200k, and it has a leaking valve cover gasket, needs valve guides and suspension work. i'm not going to get those things done (well, maybe i'll do the valve cover but it's a 6 hour job) before that car develops some other malady for which it will be abandoned in a year or two.

[Wags]

When we get that many miles on our taxis we generally run a higher viscosity grade, like 10/50.

[M>B>]

Don't change a thing, you can't improve on success!

My 1990 Tacoma V4 has 260,000+ miles on the original engine and I have had it from day one and did regular oil changes and it is going great, doesn't burn a drop of oil, but the manual tranny is another thing, spent 2G last year replacing it. The synchros in it failed and took the system down!

I have another vehicle for daily transportation, but need a truck for truck stuff, like firewood that I have to do tomorrow.

[Paul F.]

How much more life are you planning to get out of it?
Going for 300,000? 400,000? Or probably dump it at 220,000?

I'd do it. In fact, I did... Got my Nissan Pathfinder with 189,000 on it, and about the second oil change, I switched to Synthetic.

Yes, other expensive stuff may fail first...
But the engine runs good, and loses no oil.. there's no reason NOT to give it a little "edge" by using Synthetic oil that I'm aware of.

I plan on keeping this vehicle past 300,000.. maybe 350,000. Barring other major failures, I see no reason the engine won't last that.

[Dennis S]

I plan on driving it until something major happens. As long as possible.

[deckeda]

Any benefits of reduced engine wear due to less friction would have been better realized back when it was new and tolerances were tighter. So no, I'd not bother myself. I don't think it'll make it last any longer than dino oil. Even without synthetic, if it's been well cared for it should go a long time. Bought my Honda with 225K and I expect to not see significantly reduced compression, valve blow-by or ringwear for at least another 100K. And that's without knowing its history prior to 225K.

[davester]

As Paul F suggested, I'd switch to synthetic. That'll not only reduce future engine wear and further sludge formation (which is important at this stage since you're on the downhill towards failure part of the wear cycle), but it'll allow you to safely go to 10,000 mile oil changes (though 5,000 filter changes are still recommended. This should make the extra cost per oil change a wash. It's plain dumb to go synthetic and continue high frequency oil changes. You should also get a very slight increase in gas mileage, though unlikely to be measurable. Make sure you go full synthetic (Mobil 1 Extended Performance, Amsoil or German Castrol), not a synthetic blend. If you want more information on the state of your engine, have an oil analysis done and then go hang out at the bobistheoilguy forums.