cpa7man

iTrader: (2)

I've just changed the transmission fluid in my 83. After I got finished I noticed that the book said to use 90W with temps over 18c. (please no flaming) I did look up to see that I needed 2.1 qts.

I drained my amsoil 75-90 and used redline MTL 70-80, I still have the car up on the rack. Should I drain it out and put the 75-90 amsoil back in it? I've got a friend who has a shop and use his lift, but I forgot the amsoil at home.

This is an ITA car that spends most of its life above 5000 rpm.

Any opinions? Thanks in advance.

Tanjo

I used MTL in mine. Shifts smoothly, and seems to work fine.

Rx7carl

I doubt theres much difference. Why drain the Amsoil? They are both quality oils, both made from PAO stock.

cpa7man

iTrader: (2)

I had like 6 races on the amsoil. I first changed it to amsoil after I purchased the car. When I first serviced the transmission the fluid ozed out like pea soup (kind of looked like it as well).

So that was 6 months a go, I thought I would change it again. I changed the differential lube (with amsoil) than I realized I was a quart short, and happend to have 2 quarts of the MTL.....

I am just concerned about the MTL being less viscous than the amsoil. I running the 4th of July weekend and its going to be hot in College Station. I guess I'll just leave it in and see how it does.

I've been having a problem with some upshits and downshifts. I'm doing the clutch, PP & throw out bearing next week. ALso the shifter bushing. Shifting has gotten very vague and almost went into second a few times instead of third. If that doesen't fix it I guess its time for a rebuild.

Thanks for the reply's.

peejay

I use ATF.

MTL just seems to be synthetic ATF with a different label.

inittab

Okay, I'll bite. You use ATF in your manual transmission eh? why?


this should be good

cpa7man

iTrader: (2)

This is off their white paper on the redlineoil web site:

"Red Line MTL is classified as a 75W/80W gear lubricant
satisfying the API Service requirements of GL-3 and
GL-4. MTL also satisfies motor oil viscosities SAE
5W/10W/30, and the viscosity requirements for ATFs.
MT-90 is a 75W90 GL-4 and also satisfies motor oil
viscosities SAE 10W/15W/40. The additive chemistry
used is non-corrosive, so even though they will provide
GL-4 performance, they will not corrode synchros or
bushings. Because of its low corrosivity, Red Line MTL
and MT-90 could also be used in transmissions requiring
GL-1 or GL-3 lubricants. Seal compatibility is designed to
be similar to petroleum-based lubricants."

I can see where you could use it as atf. The stuff is thin. Thus my concern. I'm going to go work on my car this morning. So I'll decide what to do with the trans fluid after I replace my oil cooler lines and bleed the brakes.

peejay

I use ATF because it works.

j9fd3s

iTrader: (3)

i ran atf in my 83 for a year, it works fine. theres a lot of manual trannies that run atf or gear oil

peejay

What I mean is, ATF *works* - there are antifriction compounds in the junk that serve to increase clutch grippage - and synchros are basically just clutches.

Gear oil dowsn't "work", it just sits there being all lubey.

peejay

Additional info:

I knew that gear oil and crankcase oil are rated differently (30 weight gear oil is NOT the same viscosity as 30 weight motor oil) but I couldn't find the chart until now.

Let's see if this works...

(edit: it didn't work, see below)

ATF is about 10-15 weight on the motor oil scale.

75 weight gear oil is about 10-25 weight on the motor oil scale.

80 weight gear oil is about 20-35 weight motor oil scale.

85 is about 30-40 weight on the motor oil scale.

90 is about 40-60 on the motor oil scale.

140 is way beyond, by extrapolation around the 70+ weight motor oil range. (Yes they make 70 weight motor oil! You need it when you are racing with a crappy cast iron crank that can flop around a lot, so you have to run super big clearances in the bottom end, and then you need to run thick sludge for oil to maintain any kind of oil pressure)

joeracer

So would that be similar to the Redline xx-NS gear oils? Extra stuff to make the syncros work better.

PS Don't you just hate it when oil sits there being all "lubey"?

peejay

That is the method to the madness.

I mean, hmm, Type F (the grippiest of the ATFs) is about $1.19 a quart. MTL is about $8 a quart. Issue resolved.

Only when it needs to do other things besides lubricate and transfer heat!

Wankelguy

I've been using the Amsoil 75W-90 gear oil in my transmissions and rearends for about ten years now and it has never left me wanting for a better product.
It virtually "cured" the skritchy 3rd gear synchro in my RX4 within 6 months, and that's good enough for me.

DriveFast7

iTrader: (1)

Redline Lightweight Shockproof Diff oil in their manual tranny.

Been itchin' to try that out on the race car.

joeracer

I've been using that for a couple of years without serious issue. However, I'm about to try some MTL. I've watched a couple of my competitor's in-car video and they're shifting way faster then I am. I think the Shockproof is too slippery. Redline's website says that Shockproof may cause slower synchro hookup due to slipperiness. They recommend MTL for GL-4 needs and MTL-90 for GL-5 requirements.

-chuck-

joeracer

I checked the Redline website. They seem to indicate that ATF doesn't have the shear characteristics needed in a manual transmission.

http://www.redlineoil.com/whitePaper/13.pdf

Since changing to a synthetic transmission oil is normally a one time event, I'm not sure saving $20 on the price of the oil is cost effective in the long run.

-chuck-

vipernicus42

iTrader: (4)

I use RedLine MT-90, it's more suited for our trannies

Jon

Tanjo

Icouldnt find that around here. NOBODY had MT90, hell, it wasnt even in thier books. I woulda had to order it.

peejay

And automatic trannies don't have gears in them?

One time event? I dunno about that... see, lots of people put miles on their cars, and they have to have the tranny out every now and then. Unless you're one of those people who save the old oil and dump it back in again.

joeracer

If you READ the paper I made a reference to, you will see that Redline clearly states that the shear requirements for an automatic are different/lower. Therefore, unless specifically called for by the manufacturer, ATF is not recommended in a manual transmission. They point out that the pressures inside a manual transmission will destroy an ATF within about 5000 miles.

Save the old oil? No, I think the point I was trying to make was that I'M not the cheap one in this conversation.

My application is racing so my oil gets replaced at least every year, about every 1000 miles.

-chuck-

DriveFast7

iTrader: (1)

Hmmm.......interesting. I've had a problem downshifting to 3rd and jamming the trans in 3rd. Just shifting too fast and too hard.

Do you think using Redline Light Shockproof Gear oil to slow down synchro actuation would help in my case? Or just exacerbate the problem and start grinding gears?

joeracer

I think that the Shockproof slows down the speed matching that the synchro is supposed to do. If you shift harder/faster, you're just going to be forcing gears that haven't had their speeds matched. This would lead to grinding. If you read the article I referenced it has a lot of good information in it as to how things work in the transmission and how various oils effect this.

My conclusion is that MTL is probably the best choice. However, DON'T use MTL in your differential. Just as ATF can't handle the pressures in a manual transmission, MTL can't handle the even higher pressures of a differential. They recommend their 75W/90 gear oil for the diff.

-chuck-

DriveFast7

iTrader: (1)

thanks chuck

peejay

A) I don't trust white papers that promote something the writers are trying to sell. Conflict of interest.

B) Pretty much damn near anything will work in a manual tranny, unless of course it's one of the ones that has a pump in it (old Euro overdrive setups, some others?). I like ATF because it shifts a little better and it's cheap, cheaper even than gear oil.