Synthetic Vs Regular Oil

If you change over, change over early. Synthetic is thin and will leak through any hole more rapidly at resting temperature. Most synthetic manufacturers sell a flush to use at the time you change over. If you do this right after break-in period, you can skip the flush. Flush is known to clear out cooked on oil and can open leaks than had been previosly filled.

If you want the advantages of synthetic, talk with your mechanic about the current condition of the engine.

I think you are borderline, and may wan't to stick with the oil you have or consider a synthetic blend.

Search the board on this topic- you'll find more info than you can possibly use!

there's no more problems w/ synthetic leaking thru anymore, nowdays the syn oil got the additive, agents that fill up the gaskets to prevent that problem, i think 10k miles is a good place to start using syn, don't use it for break in that's for sure,

syn will cost more, you will probably get slightlly better performance, smoother engine operation, but nothing major, it'll reduce wear for sure and you can have longer oil change interval, for corolla, it's not a problem w/ cooked oil, engine temp doens't get so high to have that problem, you just have to weigh out your budget vs. whatever,

I changed to Mobil 1 on a used car I got with 59K miles. I never had a problem with oil leaks.

The major reason to change over (on a corolla) is to be able to go longer between oil changes. Mobil 1 can handle higher temps, last longer, and as already posted. It runs smoother and slighty improves gas milage and HP. The effect is very small, but every little bit helps. I generally run Mobil 1 because my wife drives the new Corolla and it's hard to catch a oil changes on time.

I have a turbo car that gets Mobil 1 and a Honda that gets Wal-mart oil.

The only reason to run Mobil 1 in a car like a Corolla is to run longer and that's it. It's not needed, but it does have it's advantages.

If you change over, change over early. Synthetic is thin and will leak through any hole more rapidly at resting temperature. Most synthetic manufacturers sell a flush to use at the time you change over. If you do this right after break-in period, you can skip the flush. Flush is known to clear out cooked on oil and can open leaks than had been previosly filled.

If you want the advantages of synthetic, talk with your mechanic about the current condition of the engine.

I think you are borderline, and may wan't to stick with the oil you have or consider a synthetic blend.

Also, it's hilarious to hear some people's "wisdom". Synthetic oil is not "thinner". A 5W-30 oil is just that. 5W when cold, 30W when at operating temp. Synthetic oils generally have superior cleaning properties. Many times in engines with very high miles the seals have dried and left plces for oil to leak. They don't leak because there is sludge and other deposits that "plug" these holes. When the synthetic oil is introduced, it cleans up these deposits, sometimes causing a leak.

Also, it's hilarious to hear some people's "wisdom". Synthetic oil is not "thinner". A 5W-30 oil is just that. 5W when cold, 30W when at operating temp. Synthetic oils generally have superior cleaning properties. Many times in engines with very high miles the seals have dried and left plces for oil to leak. They don't leak because there is sludge and other deposits that "plug" these holes. When the synthetic oil is introduced, it cleans up these deposits, sometimes causing a leak.

Sorry to pass off bad advise as "wisdom".

You seem to contradict yourself in your last two sentences.

PS - I've always been told that synthetic is thinner at cool temperatures, and, I believe it is one of the selling points of synthetic that it does not thicken in cold temperatures. I would suspect that a small leak in a car running dino could quickly turn into a fast leak with synthetic.

Please don't listen to my worst advice of all to "check with your mechanic".

Who in their right mind would consider that wise?

Again, apologies to all.

Best

Also, it's hilarious to hear some people's "wisdom". Synthetic oil is not "thinner". A 5W-30 oil is just that. 5W when cold, 30W when at operating temp. Synthetic oils generally have superior cleaning properties. Many times in engines with very high miles the seals have dried and left plces for oil to leak. They don't leak because there is sludge and other deposits that "plug" these holes. When the synthetic oil is introduced, it cleans up these deposits, sometimes causing a leak.

Sorry to pass off bad advise as "wisdom".

You seem to contradict yourself in your last two sentences.

PS - I've always been told that synthetic is thinner at cool temperatures, and, I believe it is one of the selling points of synthetic that it does not thicken in cold temperatures. I would suspect that a small leak in a car running dino could quickly turn into a fast leak with synthetic.

Please don't listen to my worst advice of all to "check with your mechanic".

Who in their right mind would consider that wise?

Again, apologies to all.

Best

As for my contradiction. When a synthetic oil cleans up deposits left behind, sometimes a leak will develop. This is because of the superior cleaning abilities of most synthetic oils cleaning those deposits that "plug up" around dried up and/or damaged seals. Many times it will be said..."Synthetic oil made my engine leak oil", when actually it is poor maintenance and/or poor previous oils used. The synthetic oil did what it is/was supposed to do.

That's why I suggested they ask theiir mechanic. Surely he or she might be able to see first hand by dropping the pan how things are going and give a better risk evaluation than I might over the internet.

~38,000 miles is probably too late to switch, eh?

~38,000 miles is probably too late to switch, eh?

70K? 80K? when should you decide to stay without synthetic on a corolla then?

synthetic all the way!

Seems like the logic is, if someone using sythetic then switched to conventional then back to synthentic will cause leaks ???

Is there a rule of thumb on this oilling thing ?

fishexpo101,

Any fix for this for the leaks ? I am not sure the original owner of my 4Runner, but since when I bought it I have switched it to sythentic. Now that I noticed that that some wet/oilly compound under the engine. Could that be the leak that you all talking about? If there is a leak hwo should it be fixed or should I stop using synthentic and switch back to conventional oil?