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Opeler
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Discussion Starter #1
I am in the process of changing oil in my Getrag 240 5-speed transmission. I could not find information how often the oil should be changed but I guess after 4 years and 30K miles it is time.

I am running Royal Purple synthetic oil as recommended by the shop that is rebuilding Getrags for OGTS. It is expensive (more than 3 times the price of standard gear oil). Synthetic gear oil was not used at the time Getrag transmission was in Opels. Why synthetic oil now?
What is your experience?
 

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Can Opeler
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I am in the process of changing oil in my Getrag 240 5-speed transmission. I could not find information how often the oil should be changed but I guess after 4 years and 30K miles it is time.

I am running Royal Purple synthetic oil as recommended by the shop that is rebuilding Getrags for OGTS. It is expensive (more than 3 times the price of standard gear oil). Synthetic gear oil was not used at the time Getrag transmission was in Opels. Why synthetic oil now?
What is your experience?
I used the royal purple you are using recently when I changed my 4-speed oil. I have zero leaks and everything works and sounds great. Synthetic has some better qualities than some of the conventional blends.
The Lucas non synthetics are API GL-5 rated as are the Synthetic Royal Purple API GL-5 so there’s almost no reason to pay for the more expensive royal purple. I got it because the auto parts store was out of my go to Lucas and I thought what the heck, synthetic has better cleaning and longevity properties anyway.

All the reasons to not use a synthetic in a old car are myths IMHO. As long as you use the right weight oil you’ll get some small benefits. I don’t think it’s worth it for motor oil, but I don’t want to change my gear oil again for a long time.

A lot of people argue that synthetics will eat classic car seals. This is boloney now. There were some issues with ester years ago, but now if synthetic gives you leaks it’s because your seals were already failed and the synthetic oil detergents are slowly removing the sludge that was stopping leaks.
 

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BMW dealer for Transmission Fluid?

I don't think an Opel Owner, all of us being of the same persuasion (cheap), would be caught dead going to a BMW dealer for oil we can buy at Autozone!

Allen and Vickie Gage :cool:
 

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Opeler
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Discussion Starter #6
Another reason beside the cost that made me think of switching back to standard gear oil is that synthetic oil is very thin comparing to gear oil. I am using 75-140 Royal Purple and even with good seal it can find its way out.
I would like to know if anybody is using good old standard gear oil in Getrag.
 

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I don't think an Opel Owner, all of us being of the same persuasion (cheap), would be caught dead going to a BMW dealer for oil we can buy at Autozone!

Allen and Vickie Gage :cool:
So saving a couple of bucks is more important than the longevity of the transmission ? I've always thought that a Getrag 240 in good nick is hard to find over there, but obviously I'm wrong.:) As far as I know, the Getrag 240 requires its own special oil, and I doubt it is available in a generic parts store.
https://www.edelschmiede.com/shop/Gear-oil-complete-fill-5-speed-transmission-Getrag-240-265-Opel-cih-oil
 

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Opeler
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Discussion Starter #8
So saving a couple of bucks is more important than the longevity of the transmission ? I've always thought that a Getrag 240 in good nick is hard to find over there, but obviously I'm wrong.:) As far as I know, the Getrag 240 requires its own special oil, and I doubt it is available in a generic parts store.
https://www.edelschmiede.com/shop/Gear-oil-complete-fill-5-speed-transmission-Getrag-240-265-Opel-cih-oil
We all want the best for our Opels but when Getrags were used in Asconas in 70's and 80's synthetic oil was not available. Still they lasted forever.
 

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It’s my understanding that the issue with the Getrag is that it contains brass parts that can be attacked by the sulphur phosphorous additives in differential fluid. The sulphur phosphorous additives is what gives differential fluid that obnoxious odor. These additives are corrosive to brass when hot. Synthetic differential fluids also contain high levels of sulphur phosphorous additives so the only advantage would be that the gears might run a little cooler and thus the fluid would be less corrosive to brass. The best oil to use would be s straight non-differential fluid like Mobil SHC 630.
 

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They really shift SOOO much better with synthetic oil. I’ve only used Red Line synthetics since the early 1990’s in any Opel 4-speed, Getrag, or ZF I’ve run. Night and day difference compared to dino oils.
 

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I bought my getrag years ago from OGTS, I had them do all the modifications to get it in the GT. When I picked up the transmission, Gil gave me Mobil 1 to put in the transmission. Never thought about it. It is all that has been in there ever since. Never thought about using anything else. It was given to me by one of the top mechanics in the Opel Kingdom, so that's what I use, and probably always will.

Bob
 

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Like many of us, I purchased my Getrag from OGTS. It was used and at the time (at least 12 years ago) they didn't offer a rebuild option. They either provided or recommended Mobil 1. What I noticed was when cold I had to shift slowly from 1st to 2nd or it would grind a little. Basically, I had to give it a little time for the synchro to spin up the gear. Based on comments from Rally Bob I tried Red Line. Shifting was night and day. Even though both are synthetic, the Red Line seems to have the proper amount of friction modifier and helps the synchro spin up the gears.
 

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I bought my getrag years ago from OGTS, I had them do all the modifications to get it in the GT. When I picked up the transmission, Gil gave me Mobil 1 to put in the transmission. Never thought about it. It is all that has been in there ever since. Never thought about using anything else. It was given to me by one of the top mechanics in the Opel Kingdom, so that's what I use, and probably always will.

Bob
Same deal for me. Got mine from OGTS and Gil said use Mobil 1 so that is what has been in mine ever since also.
 

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The Mobil 1 that Gil refers to is Mobil 1 75w90 LS. It a differential fluid and is loaded with Sulphur phosphorous additives. I have used it in my Getrag since 2004 without issues, but then I only put a few thousand miles a year on the car. As I said in my previous post, it may be that the synthetic aspect of that product keeps the temperature low enough to keep the additives from attacking the brass parts.

The best choice for the Getrag would be a Synthetic GL-4 rated oil. It has half the level of Sulphur Phosphorous that a GL-5 differential fluid has. Redline makes a product like that. That may be the one referred to in a previous post.

Here is an excellent article on the subject.
https://www.widman.biz/uploads/Transaxle_oil.pdf
 

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Opeler
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Discussion Starter #16
Good article. Royal Purple is not declaring if their Sunchromesh oil is GL-4 or GL-5 but it appears to be the right one for Getrag:

QUOTE:Royal Purple® Synchromax® is recommended for manual transmissions that specify an automatic transmission fluid or other light-viscosity oil. It is also ideal for transfer cases and 2-cycle motorcycle gear boxes that specify light-viscosity lubricants.

Synchromax is formulated with Royal Purple’s synthetic, proprietary Synerlecadditive technology, offering improved shift quality over a wide temperature range and reduced gear noise.

Synchromax is fully compatible with all types of friction materials and offers excellent corrosion and oxidation protection without affecting the soft metals commonly found in manual transmission synchronizers.
SYNCHROMAX® – Royal Purple Synthetic Oil

RP Max Gear that I bought seems to be well suited for differential.
MAX GEAR® – Royal Purple Synthetic Oil
 

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Good article. Royal Purple is not declaring if their Sunchromesh oil is GL-4 or GL-5 but it appears to be the right one for Getrag:

QUOTE:Royal Purple® Synchromax® is recommended for manual transmissions that specify an automatic transmission fluid or other light-viscosity oil. It is also ideal for transfer cases and 2-cycle motorcycle gear boxes that specify light-viscosity lubricants.

Synchromax is formulated with Royal Purple’s synthetic, proprietary Synerlecadditive technology, offering improved shift quality over a wide temperature range and reduced gear noise.

Synchromax is fully compatible with all types of friction materials and offers excellent corrosion and oxidation protection without affecting the soft metals commonly found in manual transmission synchronizers.
SYNCHROMAX® – Royal Purple Synthetic Oil

RP Max Gear that I bought seems to be well suited for differential.
MAX GEAR® – Royal Purple Synthetic Oil
The Synchromax is too light. It's advertised as an alternative to manual transmissions that call for Automatic transmission fluid. Automatic transmission oil is actually only 15 weight. The Getrag and stock Opel transmission should have an 80 weight oil. The other two products are Differential products (GL-5) They are probably similar to the Mobil 1 75w90 and the Mobil 1 80W140.
 

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Opeler
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Discussion Starter #18 (Edited)
Convinced

We are discussing here proper oil for Getrag but the same should be valid for standard manual transmission. I wonder how many Opels are there with wrong oil.
I spoke to several shops and car dealers in the area. It is amazing that only one technician knew about GL-5 ill effect on older transmissions. Even OGTS web page is recommending Mobil 1 LS synthetic gear oil which is GL-5.

Dropped Royal Purple MaxGear yesterday and replaced it with Redline MT90 GL-4.
 

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In the 4 speed category I’ve been using SAE 90w for 30 years, I’m glad it has that distinctive odor (don’t know if they all do)? I can tell right away if it’s a drip from the transmission or not. When I removed the pan a year ago after putting a couple hundred thousand miles on it over the years everything looked pretty darn good in there, just some very fine shavings, not much on the magnet, all of the gears were nice and shiny. One of the last mechanics who stocked parts and still worked on the Opels advised me to use it back in the 90’s, I haven’t looked back since. That said if I did have a 5 speed I’d probably be spoiling it with the best gear oil on the shelf. Straight 90w dino oil for the 4 speed and differential filled about 1/2 of an inch below the plug and they both seem to last indefinitely. I don’t bother to change it either, but who asked me anyway?
 
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