So after reading many posts i decided to rake the money and go full synthetic in the drive train. The oil of choice: Redline.

For the transmission and transfer case i got mt-90, for the diff i chose the heavyweight 75w90 gear oil, and for the engine Castrol Edge 10w30.

My only question now is how to do it?Is it necessary to drain all of the old oil, flush it, or just drain and fill? Will the redline work or break down with the old oil mixed? The transmission currently has Coastal 75w90 gear oil and the rear diff has valvoline 75w90 gear oil but as for the front diff and transfer case i have no idea since i dont ever remember my dad changing the oil in them.

I will also be installing the marlin crawler shift seats and socket along with the oil.

 

Wont hurt to take some break cleaner in there or mineral spirits to clean em out..

 

Do you mean filling them with brake cleaner/mineral spirits?
I don't understand. How will that help. Wont it hurt something?

 

He means cleaning those items with it, spray it in, dry it, etc., a rinse and flush procedure and try not to mix them with the new synth.

 

Why are you going to Synthetic.

 

ditto!

why wouldnt you?

 

If it ain't broke, don't fix it.

 

synthetic is suppposed to be better for everything..

but with synthetic motor oil..it WILL hurt your motor if you've been running regular Dino oil for 200,000 miles then all the sudden switch to synthetic..can't remember what it does..but it's not a recommended swap for high mileage motors..

but i have heard people gaining as much as 2mpg's from a FULL SYNTHETIC FLUID SWAP

which is more than enough for me..im puttin synthetic's in the 4runner whenever i get the motor broken in..lol

 

I heard in high mileage motors it can dislodge sludge around seals, mmmm instant oil leak. Then again i heard mileage does not matter. I myself have run Castrol gtx for 22 years, mm but YES synthetic does look appealing.

 

I run full syn in my 2++,+++ mile rig. Motor, tranny, t-case, front diff (the rear has a locker that hates anything but dino juice). I did have an oil leak for a while but it stopped when I went to a thicker syn.

Royal Purple is what I use. The first oil change after 10,000 miles was full of sludge and crap, the second one looked as good as the new oil going in. I'll run 5000 miles and swap the filter and add a half quart. 10,000 and a full swap.

 

And at what mileage did you swap to Syn.

 

I went and looked at the rig and I'm at 233,904 miles. I swapped at about 210,000. The 86 I had before I bought at 177,000(ish) and did the full synthetic swap the day after I bought it. Had to replace a front main seal (20 minute job) and had no leaks after that.

Why?

 

well..i guess i should have put in the post..that it doesn't ALWAYS bring up oil leaks..lol..just in some cases..hahaha

i noticed in my '80 20R that if i used a 10w30 oil..it would leak a little at a bunch of different places...but i jumped up to 20w50 (the factory recommended weight) and bango..no more leaks.............for a while..LOL

 

I'd rather have leaks than a sludgy engine.


If people would use the synthetic, the seals would probably stay good pretty much forever... and they wouldn't sludge.

 

Can you still dump your used synthetic oil in the dino oil container at a auto parts store?(I'm thinking of the ones they have at advanced)

 

If an old engine's marginal seals are depending on a layer of crud that the stronger detergents in synthetic oil will remove, switching can cause the leak to happen quicker than it would have otherwise. But, in general I agree.

My bottom end showed amazingly little wear after many years of using name brand dino oil (whatever was on sale), with oil and filter (yes, even cheapie Frams at times) changed every 3K miles. I'm thinking changing the oil regularly is as important, perhaps more so, than what type of oil you're using. Flush out the acidic byproducts from combustion, etc. I'll probably stick with dino oil after my rebuild. The lowest temps I ever encounter are above zero. If you're in truly cold climates, synthetic makes more sense.

Costwise, since synthetic is about twice the price of dino, which is better: more frequent changes of dino oil vs. running synthetic for longer intervals because it costs so much? I lean toward draining out contaminants on a more frequent basis.

I'm no expert, just throwing in my $.02.

Here's a good site for oil nerds: www.bobistheoilguy.com

 

Personally, I like changing my oil more often and it sometimes sees contamination (dirt, water) so it usually gets changed before i see the long term cost balancing. I might switch back to mineral (dino, non-synthetic) next change.

 

Well, my transmission isn't the best shifting with 286,xxx miles. Plus there is cheap Coastal gear oil in it that is probably Gl-5, when it should be Gl-4.

The 286,xxx miles are not original to the engine, it was rebuilt a while back so i don't think it will hurt. I think it probably has around 40,000 actual miles.

And all i wanted to know was the process of switching since i have already ordered the oil.

 

If you're hoping for better shifting with the syn lubed transmission you may be disappointed. When I swapped to syn on my last runner, I found there wasn't enough friction on the synchros for smooth shifting.

 

Horse carriages were fine for their time. Why should he have switched to something automated?