kmchby76

Well I found a shop who replaced my rear main seal for $470. That was definately better than paying Toyota $700+. Now I am ready for a synthetic change.

91TPU

nice...im still waiting for the warm weather to get to fix my oil leak...good thing mine isnt that serious...

mkgarrison5

what year is your truck? and how many miles. i switched from dino oil to synthetic at 52k miles.. no leaks that i know of

kmchby76

I have a 96 4runner limited with about 190k. When I first switched to synthetic, my runner leaked really bad from the main seal, so I switched back after a week. That was my only known leak at this point.

mkgarrison5

at what mileage did it start leaking?? when you switched to syn also?

BajaRunner

Dude, I hope my rear main isn't the culprit.

I've taken my truck to 3 mechanics and they can't tell where its coming from. I think its the oil-pan gasket, but, theres a chance its coming from the rear main.

So I'm gonna do the oil pan this weekend, and if that doesn't help, I'll have to be taking it to a buddy to do the rear main.

Also, my mechanic friend has been telling me that Synthetic oil is BS. He swears by Dyno oil. He made a good point: 5k synthetic oil is just as dirty as 5k dyno oil.

mkgarrison5

until you do scientific research for info on dyno or syn oil you cant just take mechanics word for it.. i agree dirty is dirty. i use syn and change at 5k miles and its butt ass nasty. but i have seen time and time again when someone takes a motor apart and see how clean it is on the inside and how bearings are in much better shape than from dyno oil

-- to answer your delima, take it to the yota place and let them put a DYE in your oil and clean the bottom off as best you can. run it for a 3-5k miles and take it back and let them use a "LIGHT" to detect any leaks. i have 80k miles on mine and i just had dye put in my oil bc i think i have slow leak near the oil pan\ rear main seal area....BUT the yota guys pointed out that since i use aftermarket filters that sometimes they leak and spray oil down the side and hitting the broadside of that large thing on the tranny making it look like rear main seal. he said the rear main seal shouldnt start no earlier than 150k miles. he said he rarely sees it

kmchby76

I think it was leaking when I bought it around 159K. I tried synthetic at about 160K.

mkgarrison5

oh well no wonder. i would stick with dyno oil that many miles.. thats just my opinion.. i bought mine with 52k miles and switched then...i have 80k miles now and supposedly all is well

BajaRunner

Yeah, I know not to take one mechanics word, and I just thought it was interesting coming from a Ford dealership's head mechanic, thats all.

He took the situation of 3rd members going out so much lately. He feels its because they are using Syn oil now for the diffs. Under compression and heat, the syn molecules tend to separate, where they should be compressing, like original dyno oil molecules do.

So what he does now is swaps out the syn oil from the factories with all the new cars, and puts in dyno oil. He hasn't gotten ONE car back since he started doing this last year. (That he had swapped out) So, I dont know if this is scientific enough, but, its pretty convincing.

Now if you want to take this and put it towards the same properties of an engine, then that might be a leap. I understand that.

Anyways sorry for hi-jacking the thread. hah

kmchby76

I know that with leaks you don't want to use synthetic, so I am assuming I should be good now that I fixed my rear main. Are you saying there is no real benifit using synthetic on higher mileage vehicles?

mkgarrison5

no didnt say that.. it could benefit it but if your dyno oil is "clogging" little holes and etc, the syn will clean this off and therefor spring a leak.. if it had that many mile why not just stay with dyno just change it every 3k miles

mkgarrison5

oh i thought you meant engine oil.. my bad.... i have no idea about differential gear oils.. i have 80k miles on my truck and just put syn in the front and rear diff and the tcase.. so i guess we will see

ARB1977

Theres this stuff called auto-rx that helps with seal leaks and is designed to safely flush out your entire engine before going to synthetic. Type in key word bobistheoilguy for more info. Its a forum geared towards motor oil.