You can switch it out the first day you get it back to your house.

 

thats scary how big of a difference there is between 2 fluids. i'm guessing the redline oil has friction enhancers and the mobil does not.

can anyone explain what exactly friction enhacners are and what they do?

 

"The synchronizer drives a cone shaped metal piece against the gear and starts the gear spinning."
http://www.innerauto.com/Automotive_..._Synchronizer/

There is a good explanation at http://members.***.net/elans4/Transmission.htm.

To synchronize, your shifter presses the inside of synchro ring 7 onto the cone 6 of the gear 5. This spins the new gear up or down to match the speed of the gear you are leaving.

The more friction there is between the synchronizer and the cone, the quicker the gear will spin up or down and synchronize with the next gear to make a smooth shift. But how can slippery oil be made to increase friction? There are additives that can do this without affecting the lubricating properties.

The synchronizer rings for each gear are made of brass, softer than steel in order to not damage the steel gears and also to be sacrificial. They are wearing parts. Speed shifting, hard downshifting, beating the synchros, poor oil, etc, will cause wear of the inside surface of synchro 7 and the brass teeth 4. Wear particles go into the oil and can be seen upon draining as a golden sheen.

 

Well, that's what I thought based on my vintage BMW motorcycle transmissions, but not so for the xB. When I changed to Redline MT-90 at 2500 miles, the OEM oil came out perfectly clean. Here's my DIY:
http://s49.photobucket.com/albums/f2...0Oil%20Change/

 

Wouldn't the Redline 75W90NS be the best for the Xa/Xb transmissions? This is from Redline oil company:

75W90 NS


This GL-5-type geal oil doesn't contain the friction modifiers for limited-slip hypoid differentials. This makes the transmission synchronizers come to equal speeds more quickly, allowing faster shifting and much easier low-temperature shifting.

I noticed a lot of people using the MT-90, but doesn't this one sound better?

BTW... I have two quarts of Mobile 1 that will have to find a new home! Thanks, for the help!!

 

I am assuming it is GL4?

I have been to almost EVERY auto parts store trying to score some GL4...impossible.

 

no... like it says, it's GL-5. The manual for my Xb says I can use either 4or5, though.

 

So the Redline GL5 contains the friction modifiers?

 

I haven't looked the Redline site for awhile, but I think the MT-90 is GL-4 and the other is GL-5, the GL-4 has friction modifiers and the other one probably as well.

GL-5 contains extreme pressure sulfur additives and was orginally designed for hypoid gear applications like differentials. The sulfur apparently can react with the yellow metal synchronizers in transmissions and shorten their life (brass is made with copper, which could combine with sulfur to make copper sulfate, a patina which would soften the surface of the synchronizers). Thus some transmissions specify the use of GL-4, while for others GL-5 is not a problem.

 

"This GL-5-type geal oil doesn't contain the friction modifiers for limited-slip hypoid differentials. This makes the transmission synchronizers come to equal speeds more quickly, allowing faster shifting and much easier low-temperature shifting. "

This is right from the Redline site for the 75W90 NS. Am I missing something? It sounds like it's made for transmissions that are synchronized (just about anything built since 1951). Are toyota's (scion) syncros made differently or of unique metals?

 

be careful - limited slip differentials are different than transmission syncros - diferentials have clutch surfaces.

 

Right... that's`why I thought this would be better for our tranmissions. We don't need the extra friction modifier's that the MT90 has.

 

From http://www.redlineoil.com/products_gearlubricants.asp it appears that the 75W90 NS is a GL-5 (sulfurous) dual-use differential oil, made without the slippery-type friction modifiers that are best for differentials, so it can also work in transmissions.

75W90 NS is a gear oil for differentials, and transmissions that have no brass and can tolerate the sulfur of GL-5:
"Red Line manufactures gear oils which can be used in limited-slip differentials without the use of additional friction modifiers... This GL-5-type geal oil doesn't contain the friction modifiers for limited-slip hypoid differentials. This makes the transmission synchronizers come to equal speeds more quickly, allowing faster shifting and much easier low-temperature shifting. Can also be used in racing limited-slip differentials where weak spring design causes too much wheel spin."

And MT-90 is a gear oil for transmissions only, especially those with brass synchros that cannot tolerate the sulfur in GL-5 oil:
"Popular in Nissan, Toyota and Mazda manual transmissions and transaxles... this is a 75W90 GL-4 Gear Oil... Red Line Oil's MTL and MT-90 are designed to provide excellent protection and improved shiftability for manual transmissions and transaxles... They have the appropriate coefficient of friction for most manual transmission synchronizers (many gear oils... are too slippery for proper synchro engagement).

 

I know your post is about 5 years old, but looks like price went up to $12.49 per/quart!

Check it: http://www.summitracing.com/parts/RED-50304/

.... potentially a higher demand on the product!

 

it's not just demand that caused the price increase..

it's the economy, oil prices in general.. and inflation.

 

yes.. yes, many potential variables , supply, etc. etc.

Well, considering this is the internet, its all about finding the product you want for the absolute lowest prices.. absolute! You don't want any one person making tooooo much profit

Looks like a dude on Amazon sell it for $11.49 + shipping:
http://www.amazon.com/Red-Line-50304.../dp/B000CPCBEQ

.... the search continues

 

a bit less: $9.95 + shipping:

http://www.racerpartswholesale.com/p...nsmission_Lube