Customer Reviews

Red Line 50304 Manual Transmission (MT) 90W Gear Oil - 1 Quart

5 star:		(35)
4 star:		(4)
3 star:		(1)
2 star:		(0)
1 star:		(0)

 

 

This is one awesome GL-4 fluid. It does everything it is supposed to and more, just as Redline promised. It smoothed out my transmission that I thought was potentially damaged. I was skeptical at first but no more. It was also cheaper than very expensive (and wrong, for my car) fluids at all the local stores that they tried to sell me.

Some background info is in order, if you are interested.

Many think all gear lube is the same, as long as you pick the right weight. Even many mechanics pay no attention to anything other than weight. Well, wrong, although it used to be true. Unlike motor oil, gear lube is indeed made different for different applications, even for the same weights, as newer cars requirements are so different from older cars.


Mistake one: I had a pro shop change the gear lube in a manual tranny pushing close to 200k.I figured it was time :) If you want it done right, do it yourself, but I was lazy that day. I specifically requested them to make sure the right synthetic fluid went in. They of course put in the right weight: high priced, major brand, synthetic 75w90, but they never bothered to check anything else, since they just have the autostore cross-reference and deliver the fluid. The stores are more clueless than anything else. The chain stores do not even stock GL-4 fluid anymore. There was one high priced brand that claimed to be both GL-4 and GL-5. Well, anything that claims to be one size fits all usually does not fit anything properly so I would stay away from that.


Mistake two: Not checking if all lube was backward compatible. If you want to be sure, check everything yourself. After all, I had professionals do it for me, right? They don't care because it is not their car. Well, GL-5 is not backward compatible and can actually damage some tender parts in transmissions designed for GL-4 due to some harsh additives.

So, after the shop put in GL-5, after a week or two, tranny started lurching in 5th gear. Darn. Did some research, but could not be sure if it was the fluid or just coincidence. After all, it is a lot of miles on the tranny. But, all indications were GL-5 was bad for my GL-4 designed transmission.
So, all my hopes rested on this Redline fluid. It did not let me down!

Got some Redline MT-90 GL-4 75w90 fluid and changed it myself. Amazon has the best price. No one locally even stocked pure GL-4. At first, the lurching was still there. Well, it was worth a try, I thought. But then, it got smoother, or so it seemed. Wishful thinking, I thought. Then, it was definitely smoother, no mistake. Could it be? Now, about two weeks after, for the very first day, the lurching in 5th gear is completely gone, and the tranny is as smooth as it was before. Even smoother. I would occasionally grind when shifting quickly, but now I can shift as fast I am capable of and I have yet to make it grind.

So, expensive lessons learned.

One, do it yourself, if you can. Check what someone else puts in your car before you let them put it there. Definition of a "professional" is that they are paid to do it, not necessarily that they do it well. Just because they get paid to do it, does not mean they know what they are doing, or know better than you.

Two, even if you do not do it yourself, at least make sure your mechanic knows what to put in. They will not take time to research and could not care less if you do not tell them beforehand.

Three, do not trust clueless autostores to cross-reference fluids. They will get it wrong most of the time. Go to factory service manuals or other reliable sources for that information.

Four, if your transmission calls for GL-4, do not chance it with GL-5! Brass synchronizers cannot take it, as GL-5 additives can eat them. You may need a new tranny or major repairs before you know it.

I had put in royal purple in my trans didn't like it to slick 3rd gear wanted to grind a little when cold in the morning. The redlline mt-90 much better the trans feels a lot smoother.When I start it up in the morning it will go right into reverse with out clutching it first.Before I always had to put it in neutral and let the clutch out once before it would go into reverse very good gear oil.I think it would be hard to find a better one.

I have had redline fluids in my cars since early 90's. Recently I switched to royal purple, simple because the nearest redline dealer is a 50 mile round trip, while RP is at nearest NAPA.
I had transmission rebuilt by a dealer after 50k miles due to grinding noise when shifting into 5th. (I had factory gear oil, changed to Royal purple at 30K miles when I start experiencing early warning signs of tranny issues). My previous experience was that by putting a better lubricant in, I was able to address early issues. Well royal Purple didn't help and dealer after being a DEALER replaced the tranny. Well fast forward 67k miles... I just start experiencing early signs of grinding in 5th. Since Redline Line was in an identical car for over 100k miles (previous vehicle, obviously the fluid was changed at the appropriate intervals) and not an issue with identical transmission.
So got couple bottles ( price was 3 dollars less than somewhat local, no tax and no driving for 2+ hours in traffic to get 2 bottles).
The shift points became a tad more pronounce almost notchy, but still smooth and NO GRINDING! So for my little Korean car the redline is a miracle fluid :)

PS Not bad mouthing Royal purple, I just flushed rear end and transmission in other vehicle... but apparently Redline was/is/will be my best option :)

I've been a longtime Redline lubricants fan because of their high quality and specific properties of the products themselves. In this case, (MT-90) the key property is to provide enough friction between gearshifts to allow the synchronizers to slow down and provide smooth gearshifts. This is not an easy task to perform while still lubricating and being slippery enough to provide a consistent oil film, lubricity, resistance to thermal breakdown and long fluid life. If you have an older transmission that's getting more difficult to shift, Redline MT-90 can improve it and extend the time before a rebuild is necessary.

Great oil! It made a big difference in my 92 Nissan 240sx. It also might of been because the gear oil hadn't been changed in a while. The old oil looked black like coffee with metal shavings! Either way shifting is way smoother now with the MT-90. If you're on the fence on getting this I say do it! It's GL-4 just what the service manual said my tranny required. If you put GL-5 it can mess with the synchros inside the tranny. Just get this and have peace of mind.

My Nissan Sentra SE-R Spec V is one of those with a transmission that grinds going into 2nd. (and maybe other gears at times.) This smooths out the shifting just fine. It is really smooth and easy without any grinding.

Highly recommended!

I've used quite a few different gear oils in my car over the years but am happy I finally settled on this redline. I was having major problems with my MT before swapping to this even to the point of suspecting bad synchros or a bad clutch but alas it is now like driving a new car all over again. The gears are super easy to shift into and out of now and as a bonus my transmission seems a bit quieter overall. I highly recommend this to anyone, it is well worth the cost.

It seems to be working fine in my NV4500 transmission, no problems so far. One bottle had leaked half of it's contents out into the box that it was shipped in however, which could have been prevented had there been any packing peanuts or something along those lines that would have prevented the bottle from getting it's top smashed to the point that it leaked.

I was in need of a GL-4 Transmisson oil for my Nissan Frontier 5 speed crew cab and no one in town carried a GL-4 oil.
I did some research and it took me to the Redline brand.
Changed out old with this and very please with shifts and noise.

I have a 1995 Nissan 300ZX Twin Turbo and replaced the 5-speed manual transmission fluid with this product and it cured my grinding of the synchros totally.