Oils for high power miata engines and gearboxes
 

Hi I got in touch with a U.K based oil specialist.
asking best oils for our gearboxes I mentioned they strip teeth when we start to make higher power so asked for an oil to try prevent this from happening.
here is what they wrote back:
Hi Derek

I'd go for a good 75w-90 ester oil for the gearbox, the Fuchs Syn 5, Millers CRX NT and Motul Gear 300 would be very good choices.

http://www.opieoils.co.uk/c-673-75w-90.aspx

I would say a good 5w-40 would probably be the way to go, unless you are getting high (over 125C) oil temps, then a 10w-50 is the best choice.

http://www.opieoils.co.uk/c-656-5w-40.aspx
http://www.opieoils.co.uk/c-659-10w-50.aspx

Out of those, the best ones are the Fuchs/Silkolene Pro S, Millers CFS, Motul 300V, Redline and Gulf Competition. They are all really good oils and up to dealing with the modifications.

Regards

Tim

OPIE OILS

For recommendations please visitwww.opieoils.co.uk


Ester oils are the top oils on the market as they are more stable at higher temperatures, leave a layer of oil over the inside of the engine/gearbox/diff (like the Castrol Magnatec adverts claim) and in general are better lubricants.

The Redline Lightweight Shockproof is also a good choice to use, it's also ester based.

Regards

Tim

"UK based oil specialist" doesn't understand that GL5 fluids aren't good in yellow metal transmissions? Disregard his recommendations.
Where is the oil analysis data? Lots of the turbo track power-hitter brute-squad run $20 Rotella Synthetic 5w40 because its cheap and works as well as the stuff that's double the price of the exotics. I think its funny that he's recommending $75/gallon oil on the exchange. Hype sells I guess.
GIII oils seem to do this just fine in modern formulation. RL shockproof is good but its too thick for street duty;AMSoil severe gear is in my car and we'll see how it does with an oil analysis soon.

just my contribution.i Iam not sure what to look for exactly thats why i asked.
The guy does offer alot of different products dont you think.....did you see any he sells that you think are suitable for the gearbox?
have a look here http://www.opieoils.co.uk/c-426-gear-oils.aspx

He recommends GL5 gear oil for a "yellow metal" synchronizer transmission, and based upon this he is neither correct nor respected. He passes the same shame over to the T5 and T56 transmissions too. I don't see anything in a GL4 on his site that I'd put in my car.

I've used shockproof or GL5 fluids in a 5 speed without too much trouble and have seen lower temps and less friction with them. No way in a 6 speed. It turns it into the chunkiest shifting box you could think of. The synchronizers in the 6speed box really dislike the Ester stuff.

Need a GL4 for the 6 speed. So far my favorite is Amsoil MTG, it is a 75W90 GL4. Stay away from anything that also meets GL5

Bob

There is a Redline and an Amsoil GL4 manual transmission gear lube on the site. I’ve tried both I think Amsoil has worked much better than Red Line for this application. My guess is everything else would not be as good or not as suitable for a Miata 6 speed. GL-4/5 is not the same as GL-4.

The 5 speed shifts so good already I would be willing to give up perfect syncro action for lower gear friction, lower driveline power loss, and lower transmission temps. Whenever I collect enough extra cash to blow on a Quafe gears for the five speed I will probably go back to a more slippery GL5 lube for the gear box.

Bob

delcbr, do not listen to anything "hustler" says, he does not know what he is talking about, at all.

http://www.opieoils.co.uk/pdfs/gear-oil-FAQs.pdf ok found out what your talking about regarding GL.
I thought we would want more EP to reduce metal to metal contact.
What do you mean by yellow metal?


What does EP mean?
EP means extreme pressure and refers to the additive used in gear oils. This additive is
designed to stop metal-to-metal contact taking place between transmission components. The
EP additives are usually based on sulphur and phosphorous. These elements bond to the
metal surfaces where there are points of extreme pressure and temperature, forming a
sacrificial chemical layer. The sulphur gives gear oils their characteristic smell.

it starts with brrr and ends with ASS

I had the same logic on my 5-speed but it got worse and worse until it would not go into 3rd gear. The AWR guys suggested 2 parts GL-4 oil, 1-part synthetic ATF in the Quaife I think...that transmission lost a few bearings and a gear after 2-seasons.

Beware of Quaife. A few years ago I bought a differential from them for my VW and immediately broke the case on the street, before ever racing the car. I called Quaife (because Autotech would not help) and they apologized because they would not warranty the case, only the gears inside. I basically bought a $900 differential, paid $400 for the install, and turned around to buy a Peloquin diff.

The synchronizers are made of Brass (yellow metal) they rely on a specific amount of friction to function properly. EP additives found in GL5 oils attack the brass readily bond to them and make them not have the correct friction level for synchronizing gears.

Bob

I tried a bunch of different oils and mixes of oils in the 5 speed. lowest friction I think was Royal purple and I mixed it with heavy shock proof hoping for more protection. It worked but it didnt stop me from blowing up seven of the 5 speed transmissions with too much torque. Broke 2nd gears, 3rd gears, and the secondary shaft drive gears stripping the teath off them.

Bob

i def lol'd as i read this.






now i gotta clean the coke that came out of my nose.

GL-4 vs. GL-5 specifications, and whether or not one is more likely to corrode certain parts of the transmission than the other. What an interesting question this is...



I just had a look at the Mazda service manuals for '92 and '99. Both of them specify GL-5 for the diff, but state (and I'm quoting exactly) "API Service GL-4 or GL-5" for the transmission.


It's getting hard to find gear oils that don't conform to GL-5, regardless of what other standards they meet. Amsoil, Mobil1, Royal Purple, Castrol, Havoline, Quaker State, Pennzoil, every single one claims either GL-5 or GL-4 and GL-5.

I think RedLine is the only one I've found that claims to be GL-4 compliant without meeting GL-5. They're actually very specific on that point, which almost makes me wonder if they're responding to fear of GL-5, rather than some specific technical requirement. Actually, what they claim on their website is that GL-5 is "too slippery for manual transmissions", not that it'll corrode the shit out of 'em.

EDIT: I finally found the one Amsoil lube out of the whole product line that's rated GL-4 without also being GL-5: http://www.amsoil.com/storefront/mtg.aspx



Although there are some interesting special cases.


Take Mobil1 "Mobilube HD Plus 80W-90", which is a non-synthetic. That lube is specified as meeting API GL-5 and ATI MT-1, but warns "Not recommended for applications requiring API GL-4 Level performance."

Curious.

I wonder if whatever additive in GL-5 compliant gear oils was causing this problem simply isn't needed in synthetic GL-5s? For instance, the data sheet for Mobil1 LS 75W140 (which is only certified as API GL-5) states that "Mobil 1 Synthetic Gear Lubricant LS 75W-140 can also be used in rear axles where API Service GL-4 lubricant is recommended"

Rear axles, but not transmissions... And yet that same datasheet says "Excellent rust, staining and corrosion protection of copper and its alloys"


Are we all in hyperspace here?

Right got you now brass lol never realised there was brass in the gearbox.so it sounds like there's no hope for saving my 5 speed from self destructing.what power levels have you been destroying gearboxes 7 is alot!

did you pull back on your joystick?

I just picked up two quarts of the Amsoil synthetic gear lube without reading the label. By accident, I got the FGR which is the GL-5 75-90.

I will be going back to the store tomorrow and exchanging it for the MTG 75-90 which is GL-4....

incidentally, the equivalent redline GL-4 product is apparently the MT-90 you alluded to above.

Over 300 ft-lbs and race rubber and your 5 speed gear box will have a very limited life has been my experiance. The right gear oil will not save you, smooth shifting will not save you, not using the gas pedal all the way might but wheres the fun in that.

Bob

I enjoy BG syncroshift. I put it in all my transmissions.

All I know is what I have tried. Amzoil MTG 75W90 GL-4 made the 6 speed feel way better than any other oil I have tried. even a swap from Redline MT-90. I have seen the other gear oil Nut jobs harping on GL4 - GL5 differences on Miata net and always dismissed them in the past. Did the swap on a couple 6 speeds now and noticed a huge difference. Could be just that it is Amsoil but the fact that it is GL4 and not GL5 might have something to do with it. Never noticed that much difference in any of the 5 speeds with a gear oil change.

Bob

The AMSoil is a bit thicker at 200*f than the Redline.

I know the Mazda FSM/datasheet says GL-5 is acceptable. This is where ultimate intelligence and I depart. I know GL-5 is "safe" but I've ruined a few transmission from running GL-5 oil in my Miata and VW's. There are a few GL-5 oils which specifically state they are safe for yellow metal synchronizers, Mobile1 is one of them, and I ran that in my 5-speed with synchronizers that don't work on a few gears, I've also seen them opened up and its obvious that synchros were eaten. I have a paper on it somewhere...