We recently purchased an '01 Toyota Sequoia (4.7L V8). It's got 70K miles on it. I know I've read of problems with some higher mileage vehicles running into problems when switching from conventional to sythetic(leaking and such), but I think it was mainly GMs. Could you envision any problems switching my truck over to synthetic, or should I go for it?

The Oilman will chime in,

But I would go for it!

That's my thought, too, but I just got rid of one car that leaked oil all over my garage floor. I'd like to avoid that again for a while

If a car does not leak oil, it will not leak oil.

I never gave much credence to the small molecule/slippery action of synthetic leading to easy leakage. I have run synthetic in cars that where tight as a drum and never even had seepage.

I never noticed any leaks either, but unless your goal is extended oil change intervals, synthetic is not worth the effort or money. These new engines are so efficient, I wouldn't worry about it either way.

Well, that's your opinion. I could definitely tell a difference when I switched my Accord over. Not to mention, not changing the oil every 3000 miles is nice.

Sorry, I didn't notice it was a Toyota. Most foreign cars call for synthetic, don't they? With the smaller cranks, connecting rods, aluminum parts, etc.., maybe that is the reasoning.

Yes, it was my opinion. I should have added that.

Nope.

Toyota uses conventional Mobil.

This is the approach I've taken in the past when I've switched to synthetic on used vehicles I've purchased. It's held true so far.

I normally get on FM for a while in the evening - this thread has already gotten a number of responses, several of which I will also comment on here.

Any Toyota with 70,000 is not high mileage in my opinion, and should be absolutely no problem changing over to AMSOIL.

A general overall statement - you can use/change to AMSOIL (or any other synthetic) in any sound engine. That is, one that does not use, burn or leak an excessive quantity of oil. You will have to use your own definition of 'excessive.' Some people consider a quart in 3000 miles excessive, some a quart in 10,000 excessive, I even had a Ford dealer/service manager tell me a quart in 500 miles in a Mustang was not excessive (boy do I consider his opinion way out of line). I sell oil to a number of fleets that with older trucks use the 3000 number - if more than a quart in 3000 miles they don't change to AMSOIL.

A comment about 'so slippery it will leak past a seal' and another one I hear occasionally - AMSOIL caused my seals to leak. I have seen a few that after changing to AMSOIL in a higher mileage engine that seals started leaking. AMSOIL will clean sludge, gum and varnish out of a dirty engine and if that is what was holding a tired, worn out seal together, then you will probably develop a leak. But the oil didn't damage the seal - it was already in bad shape - AMSOIL just revealed it. I have seen a number of the older GM 4.3, 5.0 and 5.7 engines that AMSOIL cleaned from the valve guide seals, and in worst case an engine had to have a head job done.

Fuel economy? Most of the synthetics on the market will boost fuel economy around 2% or 3% - that is Group III, which are actually a super manufactured version of a regular petroleum based oil. Which ones are Group III? all the store brand, and most of the major oil company brands except Mobil.
Group IV base synthetics, which are fully designed and build oils - PAO base, will increase fuel economy more. AMSOIL will do better than Mobil giving at least a 5% increase in most cases.
At $4.00 per gallon (and we are getting close now) that means 20 cents saved for every gallon bought, or $2.00 for every 10 gallons. A small car using a 10 gallon tank per week means $8.00 per month!

And fuel economy is only part of the savings. AMSOIL will reduce wear - by around 50% - as compared to petroleum oils. With around -60 deg F pour points it means much easier winter starting, but it also protects on the high temperature end better too. It will reduce engine oil temperatures 30 to 50 degrees - which takes stress out of a lot of engine parts. It means seals will live for much longer!

not changing the oil every 3000 miles is nice.

And not having a bunch of containers of drain oil sitting around,better lubrication,cold starts,mileage.....