https://cdn.opieoils.co.uk/images/variants/medium/redline/red-line-mt90-75w-90-gl4-synthetic-manual-gear-oil-1-us-quart-0946-litre-1.jpg https://cdn.opieoils.co.uk/images/variants/medium/redline/red-line-mt90-75w-90-gl4-synthetic-manual-gear-oil-1-us-quart-0946-litre-2.jpg

https://cdn.opieoils.co.uk/images/variants/icon/redline/red-line-mt90-75w-90-gl4-synthetic-manual-gear-oil-1-us-quart-0946-litre-3.jpg Satisfies the gear oil viscosity requirements of 75W90, 80W90, 90 and engine oil viscosities of SAE 40, 10W40 and 15W40 This 70W80 GL-4 Gear Oil (SAE 5W30/10W30 engine oil viscosity) is designed for use in manual transmissions and transaxles. Provides excellent protection of gears and synchronizers and its balanced slipperiness provides a perfect coefficient of friction, allowing easier shifting. Popular in many BMW transmissions and in most Honda and Acura transaxle applications. Several here, including myself, have used motor oil in X transaxles, often in lower viscosities than MTL. Bur MTL works better, regardless of weight. It's one of those rare products that works as claimed.

Check Compatibility

https://cdn.opieoils.co.uk/images/variants/icon/redline/red-line-mt90-75w-90-gl4-synthetic-manual-gear-oil-1-us-gallon-378-litres-1.jpg Thinking about this one a bit more, could it be that those folks who claim that their tranny shifts "better" when filled with fresh MTL Redline fluid are actually reacting more to the use of the lighter weight oil, rather than some mystical chemical properties that Redline offers and that other oil brands do not? Popular amongst rotary owners Redlines MT-90 is a GL-4 Gear oil suited for your transmission/gearbox. Being GL-4 its ideal if your worried about the risk of some GL-5 oils prematurely/rapidly wearing or damaging your synchro’s (please note that Idemitsu Racing MTF 75w90 is a GL-5 that will not prematurely/rapidly damage wear your synchro’s)Something that cannot be said for all GL-5 Gear Oils when put in some transmissions like those found in the RX-8

Appropriate coefficient of friction for most manual transmission synchronisers (other’s synthetic gear oils are often too slippery for proper synchro engagement) Recommended for GL-1, GL-3 and GL-4 applications, as well as where most special synchromesh fluids are specified https://cdn.opieoils.co.uk/images/variants/medium/redline/red-line-mt90-75w-90-gl4-synthetic-manual-gear-oil-1-us-quart-0946-litre-3.jpg

Translate:

I found MTL around 20 years ago while trying to solve some crunchy gear engagement problems in a BMW. It solved the problem so well that I've been a Redline fan ever since. It ain't snake oil. It's an engineered product. IIRC, Redline says flat out that the only difference between MTL and MT90 is the viscosity/intended temp range. Like Steve says, if the car is driven hard or lives in a hot climate, MT90 is prolly a better choice. But frankly, we've run MTL in BMW race cars where the trans tunnel actually gets too hot to touch in the summer, and never seen a problem. https://cdn.opieoils.co.uk/images/variants/large/redline/red-line-mt90-75w-90-gl4-synthetic-manual-gear-oil-1-us-quart-0946-litre-1.jpg RED LINE MT-90 HIGH-PERFORMANCE GEAR OIL is a fully-synthetic ester-based lubricant designed for use in manual transmissions and front-wheel-drive transaxles. This shear-stable formula resists breakdown for extended periods and offers more consistent viscosity in warm and cold temperatures for less gear noise and improved shifting. This fluid is less slippery for improved synchroniser coefficient of friction and offers stronger film strength for better wear protection.

Appropriate coefficient of friction for most manual transmission synchronizers (other's synthetic gear oils are often too slippery for proper synchro engagement) Where I live I'm a fan of MT90. But if you drive your car when it's cold outside MTL would likely be the best choice. If you have any doubts just call Redline-- I'm sure they'd happily advise you. In any case, you won't be regret installing either MTL or MT90.

Car Service Packs

https://cdn.opieoils.co.uk/images/variants/large/redline/red-line-mt90-75w-90-gl4-synthetic-manual-gear-oil-1-us-quart-0946-litre-2.jpg https://cdn.opieoils.co.uk/images/variants/large/redline/red-line-mt90-75w-90-gl4-synthetic-manual-gear-oil-1-us-quart-0946-litre-3.jpg https://cdn.opieoils.co.uk/images/variants/icon/redline/red-line-mt90-75w-90-gl4-synthetic-manual-gear-oil-1-us-quart-0946-litre-1.jpg High performance gear protection giving longer synchro life and eliminating notchy shifting, even when cold. Satisifies the gear oil viscosity requirements of 75W, 80W and motor oil viscosities of SAE 40, 10W40, and 15W40. Recommended for GL-1, GL-3, and GL-4 applications, as well as where most special synchromesh fluids are specified. Appropriate coefficient of friction for most manual transmission synchronizers (other's synthetic gear oils are often too slippery for proper synchro engagement). This Gear Oil is suitable and popular for most RX-8 and RX-7 Transmissions. MT-90 75W90 GL-4 GEAR OIL

I switched to redline MT90. That didn't cure the o/drive problem but the transmission seemed to shift a little smoother... RED LINE MT-90 HIGH-PERFORMANCE GEAR OIL is a full-synthetic ester-based lubricant designed for use in manual transmissions and front-wheel-drive transaxles. This shear-stable formula resists breakdown for extended periods and offers more consistent viscosity in warm and cold temperatures for less gear noise and improved shifting. This fluid is less slippery for improved synchronizer coefficient of friction and offers stronger film strength for better wear protection. An old post by Keoke on this forum recommended Valvoline VR1 60W in the summer and 50w in the winter. I put in 60w and that fixed the o/drive problem that you described on my car. If MT90 fixed it on yours then your accumulator seals are not quite as worn as mine apparently are.

Maybe I could do a 50/50 mix of MTL and MT90, which would give me a viscocity more or less in the middle ... the best of both worlds ... ? I think that Dave said MT90 is somewhat equivalent in viscosity to 40w motor oil. If your o/drive starts acting up again when it gets real hot, try switching to 60w valvoline VR1.