This will be my first oil change in my FJ-40 with a newer 1F...the previouse owner had been using Mobil 1 Synthetic.
It does not leak a drop of oil, and runs great. Would I be messing up by switching to a 10w-30 sythetic blend?
If I do switch, should I flush the system with a crankcase of oil, and run it for a little, then put in a new filter and put in the synthetic blend?
(hey, if it screws up the engine, then theres a good reason for the v-8:D )
Thanks

Joseph A.

BTW...since I now am not a newB...who can resize a picture for me to make it a avatar? Plz e-mail me or send me a PM...
Thanks :D

Joseph A.

TxCruzr, I would stick with the Syntho. Fully synth (mobil 1) Blended, and Regular Oil all have different swell rates, so above and beyond the pinging you might notice you'll probably spring a few leaks also. But of course if you don't give a crap about a non-leaking 1F (Rare) then by all means go ahead and run whatever you feel like running.......Mobil 1, even though it's pricey is the best. We run it in our Hunter UAV Aircraft that has 2 1000cc Moto Guzi 4 strokers in it, I've never seen one leak or seaze.

I have heard of mixed reviews dealing with compatbility with synthetics verses standard oil.
Recently a person I know switched from regular 10W40 to Mobil 1 synthetic, Immediately he noticed and saw a difference. Upon start up his motor started tapping until it warmed up. Also he noticed front a rear seals began to leak. This wasn't the case with the standard 10W40 he was using. Switched back to his usual standard engine oil and the noise and leaks stopped.
The next story involves a motorcycle....switched from standard oil to synthetic...while driving there was no problem, but when he stopped at a light, his motocycle would overheat....changed the oil back to standard brand and the overheating stopped....The synthetic didn't work well in carrying away the heat....
I have read that there is seal compatability problems when switching from one type of oil to the other. Some seals do not hold up to the synthetics... Especially trying to run it in brake systems not designed for it....
Take this info for whatever its worth..personally I don't see the benifits of running synthetics, to me the cost is not worth it...To me oil is oil, as long as you change your oil at acceptable intervals you won't have any problems running good old standard oil... :skull:

Break-in should always be done with dino oil. Apparantly, synths do not allow sufficient wear for break-in. Personally, that is reason enough for me to use synths. I've heard that going from dino to synth is ok but going back is not a good idea. Obviously there are contrary opinions on this. I have had very good luck with synths and will continue to use them.

i too like synthetics, and cost is not really an issue since oil changes with synthetic take place every 6-7k miles instead of 3-4k. at least for me thay do.

I switched my FJ to Castroil Syntec and had good results (quieter, smoother running). I do have the above mentioned problems though...new seals that still leak, oil pan gasket leaks:D

You shouldn't see any problems going from synthetic to normal oil. Just change the oil every 3,000 miles or every six months.

Biggest issue is when you have been running regular oil for year and go to a synthetic. The synthetic has a much higher detergent to them, but will start to remove all the sludge and shellac build up. Not uncommon to hear of those engines leaking like pigs after a few months of synthetic oils. Also if there was lots of sludge you run into the problem of the oil pickup screen getting clogged up.

Typically after rebuilding an engine I'll stick with straight 30W non-detergent. Change after 10 minutes to catch any lint, etc. Next change at 500 to 1000 Miles. Then start running either a good 20W-50 multigrade or synthetic.

One item overlooked with pure synthetic, not really that good for "occasional use" engines. The synthetic will run off the metal a little easier, dino oils leave a better film. General Aviation Aircraft are good examples of something sitting for a few weeks, then run over a weekend. Excessive camshaft wear from start up lead to Shell developing the synthetic blend.

So if you have a high mileage motor, I'd stick to the good multigrade 20W-50. If the engine has recently been rebuilt, then break in on non-detergent 30W, then go to the oil of your choice.

Tom :usa: