Oil question

[och]

So this topic has been debated to death, but yet again I'm opening another thread.

I'm looking for everyones suggestion on what type of oil to use. I've been using Mobil1 full synthetic in my 01 GS430 and there's not a single leak anywhere, the car now has about 115k on the clock.

However in my 94 LS400 I've been using conventional 5w-30 oil. And in fact it had a pretty bad leak from one of the cam seals and both cam covers. I've recently replaced both cam seals and both cam cover gaskets. Also, I replaced crank seal about two years ago. The car now has about 125k on the clock.

Do you guys think it would be wise to switch to synthetic oil now that I've took care of most these seals? I know there's the rear main seal that can potentially leak, but I haven't seen any leakage around it, so I'm hoping it wont.

Also, what about Mobils clean and high mileage products? Supposedly they have seal conditioners and cleaning agents, but I don't think they are necessary at all in my case since most of my seals are not new. Also as far as cleaning, when I opened my valve covers, the valve train and all the oil veins were perfectly clean, with no sign of sludging.

But then again, there are also internal seals such as valve seals and piston rings and if they are worn, could the engine start burning oil? It is not burning any oil now.

And another concern. When I was replacing the cam seals, I saw a little bit of oil seeping through where the oil pump connects to the block. I wasn't up to the task of resealing it, so I left it alone, and I'm just keeping a close eye on it. Of course I cant see the oil pump with all the parts back on the engine, but it seems that theres no oil making its way down to the bottom of the block, everything is dry, so I assume its nothing major.

 

[cribbj]

The synthetic will probably find all the little leaks that have been conveniently sludged up by the dino oil.. My '94 Supra burned no oil when I bought it at 55K, but when I switched to Mobil1 at 60K it started smoking at startup.

Turned out it was the valve stem seals, and once those were replaced, no more smoking.

I think synthetic oil has some real benefits for a turbocharged car, or a continuous duty, high output, industrial engine. But for a naturally aspirated, daily driver that already has 115K on the clock, you may be opening up a can of worms.

 

[gloverman]

Heres a suggestion for you. Find a high grade mineral or semi synthic that you like and stick with it. Everyone has there own opinions on which oil is better.
Personally I use ELF 15/50 competition GT in all my lexus motors ( I own a workshop and so work on alot of them )
They work perfectly well on 15/40 Super sporty mineral oil and 10/40 comp GT semi as well.
I like the 15/50 as they do tend to generate alot of heat under the bonnet so theres a bit more protection for that.
At the end of the day most high grade oils will work well. I tend to stay away from the full synthetics as old lexus motors do tend to burn a bit anyway.

Remember just my opinion.

Cheers