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914World.com _ 914World Garage _ Gear oil 75W-90 - Synthetic or Not?

Posted by: surfdogskier Dec 1 2020, 08:46 AM

Hey guys, my ride has started having issues going into gears cleanly. I hope it is just the gear oil. I have never changed it since finally getting her running so I expect it to be quite old. I got it all drained.

My question. Should I use synthetic or not. Back 15 years ago on posts, it read don't use but then I find others saying they are. I figured synthetics have gotten a lot better since then. I bought synthetic but having my doubts until I here some recent opinions.

I purchased Synthetic 75W-90 GL-5 Gear Oil. 3 quarts.

Posted by: Steve Dec 1 2020, 08:53 AM

Never use synthetic in a Porsche 901,914 or 915 transmission. It’s too slippery for the synchros. Use standard 90 weight gear oil.

Posted by: surfdogskier Dec 1 2020, 09:04 AM

QUOTE(Steve @ Dec 1 2020, 09:53 AM)

Never use synthetic in a Porsche 901,914 or 915 transmission. It’s too slippery for the synchros. Use standard 90 weight gear oil.

That is what I needed to know. Swapping it out today....Thanks!

Posted by: Mikey914 Dec 1 2020, 12:39 PM

One place cheaper is better! Don't see that too often.

Posted by: mlindner Dec 1 2020, 02:36 PM

Again, read any of Dr. Evil's comments on this. Dino oil only. No synthetic.

Posted by: Bulldog9 Dec 1 2020, 02:47 PM

I've been using Swepco 201 in my transmission. Made an immediate improvement, and it just keeps getting better and better.

I have a buddy who swears by Redline heavy shockproof, but it is synthetic.

Posted by: surfdogskier Dec 1 2020, 04:35 PM

QUOTE(Mikey914 @ Dec 1 2020, 01:39 PM)

One place cheaper is better! Don't see that too often.

Definitely true there....It was half the cost when I swapped it out.

Posted by: Mark Henry Dec 2 2020, 11:23 AM

This is close to 20 years ago but I did have OK luck with Kendall semi-synthetic.
I prefer Kendall but any cheap dino will do.
The only thing I liked about swepco was the pretty blue dye made it easy to spot a trans leak. IMHO it made shifting worse, but I still like the 101 grease.