Hello, I will have 257k miles when my next oil change is due. Should I switch to synthetic 5w-30 oil? I have been using synthetic blend 5w-30 in the past few oil changes. I live in Florida so the coldest it ever gets is in the high 30's for maybe one week per year. I do not think my engine is burning oil (knock on wood) so would this be a good idea? I also did a major gasket service last year at 247k miles so I think most of the gaskets are in good shape.

Thank you.

Sure you can switch. Is it going to make a mind-blowing difference with the amount of wear happening to your engine? Probably not. I made the switch to full synthetic recently myself but it was mainly because I wanted to extend my oil & filter change intervals. I use to follow the old school suggestion of changing my oil and filter every 3k miles when I running a partial synthetic. I've now upped it to every 5k running full synthetic oil. I know, I know, I know guys I could get more miles out of my oil when running full synthetic. An oil sample sent to Blackstone Labs would probably confirm this but I don't care. It makes me feel better that I'm giving my engines a more regular oil and filter change.

As someone of your generation, I too found it hard to go beyond the 3k mile interval to 5k and beyond. The extra cost of synth oil is offset by the longer interval, so it is beneficial to move to synth oil.

Presently using HM full synthetic oil in the 4Runner and a k1500, a 99 and 98, no leaks and clean valve trains.

The only caveat about using full synthetic is that in older engines it can exacerbate leaks that were present using conventional.

I have 160,000 and switched to synthetic. I have since switched back after 1 oil change due to oil consumption and leaking.

My truck went from not consuming or leaking any oil into burning almost 3/4 quart 1000miles after full synth oil change.

Since I've gone back leaks and consumption have also stopped.

My .02c

I agree with the other posters in this one. I learned the hard way in the 90s. I went to full synthetic on a 1983 Toyota 4x4. Well needless to say I had to switch back to conventional on it as it would not stay in the engine.

I ran castrol synthetic blend High Mileage on my 4 runners and that seem to stay alright.

On the next oil changes I going to full synthetic castrol magnetic. Will I seep a little oil. Probably, but like Tim says we cant beat how synthetic oils basically super slow down wear.

I change my oil every 5k. Rotate the tires and check the brakes out too. I mostly check my spare tire air every 10k. Nothing worse then having a flat spare tire.

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Maybe try to goto 10w -30 full synthetic. Mostly, if we go up a grade it is a little thicker. Might help with the leaks. Or you can just stick with conventional. :]

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Are you asking if its okay to run 5w30 synthetic if the temperature dips down to 30 degrees? Or just stick with your 5w30 synthetic blend? I ran 5w30 synthetic blend all last winter and it got as cold as -40 with the wind chill and it just needed extra time to warm up. You can keep running the synthetic blend all "winter" in florida. Its frequently below 30 here all winter and thats what I run in mine. I think this was what your question was? Cheers!

Since you've recently had the gaskets replaced switching to full synthetic is fine. I think others have already mentioned but you probably won't notice much difference other than your oil change interval.

I got my 97 with 225K, I put it amazon basics high mileage full synthetic 10w-30 and all has been good so far. My only complaint is that its hard to read on the dipstick it is so clear. I believe Warren makes their oil, from what I read it seems to be on par with the big name brands.

Same thing happened to my 2005 SR5 with 145,000 miles. Changed back to conventional - leaking drops in garage stopped.

switched to full syn at 145k, now at 202. Longer intervals was one reason, but the better wear and tear the other. Ive been running amsoil and did the first oil change at about 3k "to flush it" and it came out kind of dark. Next change less dark, now oil changes at 5-7k come out clean like almost like new oil. Last summer I had to do knock sensors and did vc gaskets too...I was surprised how clean the valve train was.

My buddy is a mechanic in Oregon and told me that with 2nd and 3rd gen 4runners to just use the cheapest conventional oil and change it every 3000. I know some people say they get better gas mileage with full synthetic, but I find that hard to believe.

Why... oh why do people insist on bumping Dead threads? You want to get your post count up, do it in one of the dedicated "trash" threads.

Oh, I could careless about post count. I am just searching relevant topics to me, and commented. Wasn't trying to break forum etiquette.