Hello, I am going to change all my fluids to synthetic what is a good weight for front diff rear diff, engine and powerstering pump I have a 1991 3.o 4runner with auto and is there any other fluids I should change to synthetic.Thanks for you time .

 

the horn fluid gets low time to time....

sryy ... transmission maybe?

 

dont forget about the blinker fuild..... transfer case ?

 

Ya'll are MEAN!

I think the factory manual recommends 75w-90 in most cases. Don't forget the transmission & transfer case. Do you have manual or automatic? What is your temperature range where you live; that will have some to do with what weight you want to use....

 

we made positive suggestions also, and he has an automatic as stated

 

haha you guys are mean!!
have you a owner's manual for the truck? or at least a repair manual? if not then shame on you!! but regardless, i am SURE that if you did a "search" you could find what you are looking for on here.

 

I live in Houston TX,the reason I am asking is I have seen alot of different opinions about this. I have 189,000 original miles with the same engine and tranny but I have heard some owners were raising there fuel milage when they changed and I am mechanicaly inclined I know there is no blinker fluid and so on I was asking for some recomendations not banter! I have an owners manuel and there is nothing listed about synthetics that is why I was Asking.

 

^^^ of course there is not going to be anything in the owners manual about synthetics. you asked about what weight to change to, i said to refer to the owners manual. the weights will be the same, only differance is you might be using synthetic. word of caution though... with as many miles as you have on your engine..... DO NOT change to synthetic oil in the crankcase. do a search and you will know what i am talking about. you might cause leaks to form!
as for your power stearing goes, it is pretty much ATF. (automatic transmission fluid) and should be left alone.

just food for thought, in my transercase, front/rear diff, tranny,engine i have Lucas Oil. so far no complaints, but i think i will change it out to something else in the next few months, just to see what something else will do versus Lucas Oil. There are some good write ups here about oil addatives. just take some time and "search"

 

The problem with switching to synthetics on older vehicles is that synthetics actually will clean out sludge where a gasket used to exist and you'll often end up with leaks where before you had none. this is of course in the engine and that is where oil would most benefit you.

For manual trannies, no biggie...for autos, I'd suggest staying away from synthetic because it inhibits the operation of the transmission, especially in older transmissions with worn parts.

 

uhhh... yeah.... like what i said

 

Oh brother.... check out Bob is the oil guy If you can run regular oil in something with the same viscosity, then you should be able to run the same grade with synthetics. My Automotive Instructor only recommends using synthetics "if you don't like to change oil/fluids all of the time. If you don't mind changing oil/fluids then cheap is just as good as long as it has an API symbol." David Hollingsworth, with YEARS of automotive and airplane mechanical experience.

 

If you havent checked this write up out, you really should.

Sweet write up.

Between this writeup, the toyota manual, and the local amsoil guy, replacing all the fluids over to synthetic was a sinch. As far as I can tell, auto trany's are a pain in the ass. Good luck with that.

p.s. I switched at 150,000 km. After 6500 km, the engine oil is still full and light brown. Synthetic is nice!! The rolling resistance is much lower as well, thanks to the diff, tranny, and transfer case oils. I am tracking gas milage to see if it made a noticable difference.