What weight of oil to use?

[billy bronco]

Hello,

Can you advise whats the best oil to use here. Seems if Im reading the book right it call for 10W-30 for above 50 degrees, this sound right?

Also for the rear end what is API Service GL-5 is this just a fancy name for 80W-90 ?

Looks like the tranny & rear end use standard 80W-90, Am I right?

Thanks

 

[KpaBap]

I used Mobil 1 75w-90 in the tranny and in the differential, and use Mobil 1 10w-30 in the engine. API Service GL-5 compliant oil is what's required, and Mobil 1 fits that bill. Regular 80w-90 should be just fine as well as long as they are GL-4/5 compliant.

 

[billy bronco]

I used Mobil 1 75w-90 in the tranny and in the differential, and use Mobil 1 10w-30 in the engine. API Service GL-5 compliant oil is what's required, and Mobil 1 fits that bill. Regular 80w-90 should be just fine as well as long as they are GL-4/5 compliant.

Thanks, I changed the oil & filter last nite and used 10W-30, glad to here it was the correct weight. Man, what a pain to get at that oil filter though. I would like to change the other fluids while I have it up on ramps, hope I can get the GL-4/5 stuff at auto zone. This code is new to me as I don't often deal with these heavy weight oils. I looked on an old bottle of the cheapest AZ 75W-90 "Coastal" and its compliant, I will just buy some Mobil or brand name, guess it can't hurt.

Thanks

 

[B.L. Zebop]

Engine oil can vary from 0W30 to 15W50...but 10W30 should be fine.

As to the transmission, I'd highly recommend Redline M90 (or MTL if you want something a bit thinner). Both M90 and MTL gear oils are specifically designed for use in transmissions / transaxles and are far better than straight gear oils. M90 is a 75W90 weight, while MTL is a 75W80 weight (better for winter).

For the diff, again Redline, though in this case their 75W90 gear oil.

Go to www.miata.net and into the Garage section...all is explained.

 

[Bender]

The quick and simple:

Use 10w30 in the engine.

A tranny oil like MT90 in the transmission.

A diff oil like Redline's 75w90 (NS or non-NS) in the differential. Do you have LSD? Just because you can use it in the transmission, doesn't mean you should use it in the differential.

Go to a speed shop and they should be able to help you out.

 

[goldstar]

Hello,

Can you advise whats the best oil to use here. Seems if Im reading the book right it call for 10W-30 for above 50 degrees, this sound right?

Also for the rear end what is API Service GL-5 is this just a fancy name for 80W-90 ?

Looks like the tranny & rear end use standard 80W-90, Am I right?

Thanks

The API (American Petroleum Institute) Service rating of a transmission oil refers to the amount of EP (extreme pressure) additives it contains. An API Service GL-1 oil contains no EP additives and a GL-4 service oil contains about 1/2 the EP additives of a GL-5 service oil. EP additives are composed mostly of sulfur/phosphorus compounds which can harm yellow metals such as copper or brass which are contained in some synchros. Protege synchros do not contain yellow metals and consequently, as clearly stated in the FSM, either GL-4 or GL-5 oils are completely safe to use.

The API Service rating is completely independent of the viscosity rating so, for example, an SAE 75W-90 oil could be a GL-4 or a GL-5 or even a GL-1. In terms of viscosity the FSM for a Protege specifies 75W-90 for the transmission for all season use. Red Line MT-90 is a 75W-90, GL-4 oil.

 

[billy bronco]

Well, I changed engine oil and used 10W-30, wow did it quiet her down runs better. For tranny and rear end I used Castrol Hypoid 80W-90 rated at better than GL-5 for both tranny & rear end, hope this is okay. Car will not be driven in the winter months.

 

[B.L. Zebop]

For tranny and rear end I used Castrol Hypoid 80W-90 rated at better than GL-5 for both tranny & rear end, hope this is okay.

Nope, it's not ok... (hand) you will need to a transmission flush. That's meant for differentials and non-synconized transmissions...it will eat your brass synchros. To quote Castrol's info:

Hypoy C 75W-90: exceeds API Service GL-5 and API Service MT-1 lubricant for extreme pressure conditions and provides superior low temperature performance for smoother gear shifting and differential operation in colder climates. Maintains a thick oil film even under high temperatures and is recommended for service fill of all limited slip differentials calling for an API Service GL-5, SAE 75W-90 gear oil.
<LI>Hypoy C 80W-90: exceeds API MT-1 lubricant for
non-synchronized manual transmissions used in buses and heavy duty trucks as well as API Service GL 5 lubricant for extreme pressure conditions. Recommended for service fill of all limited slip differentials in passenger cars and light trucks calling for SAE 80W-90 and API Service GL-5 specifications. Recommended for applications calling for Ford ESP-M2C154-A and GM 9985290 and is Mack GO-H approved.

GET IT OUT OF THERE NOW!!!(hand)
Personally, it's also too thick for your diff too.

 

[APEXistud]

I used 15w-50 over the summer mainly to quiet down the HLA's until I can repair them. After that, I'll probably use 10w-30. A filter relocation kit would be beneficial on your nuckles. As for the tranny oil, I took the advise from Rishie at AutoR&D. He recommended Redline MT90.

 

[billy bronco]

Nope, it's not ok... (hand) you will need to a transmission flush. That's meant for differentials and non-synconized transmissions...it will eat your brass synchros. To quote Castrol's info:
GET IT OUT OF THERE NOW!!!(hand)
Personally, it's also too thick for your diff too.

I was hoping I would not hear that, what can I buy at my local AZ for the tranny that is correct? They have API-GL/5 approved 75W-90 general purpose (Coastal) stuff. I will change it ASAP, drive it a while and change it again. Pehaps the second change I'll get the Redline stuff.

You say the rear end is fine with this Castol, right?

 

[billy bronco]

this the stuff?

Redline MT90 (Gear Oil)
$8.00
620-022

"MT-90-Manual Transmission Lubricant- a 75W90 GL-4 gear oil 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."

75W90 GL-4
]

 

[goldstar]

this the stuff?

Redline MT90 (Gear Oil)
$8.00
620-022

"MT-90-Manual Transmission Lubricant- a 75W90 GL-4 gear oil 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."

75W90 GL-4
]

Yes, that's the correct oil.

02 DX Millenium Red

 

[billy bronco]

Yes, that's the correct oil.

Okay, I plan on odering below oils. Can I just replace the Castol with this stuff and be okay, someone mentioned flushing?

RED-57904 Red Line 75w90 Gear Lube - for rear end
RED-50304 Red Line MT90 - for transmission

 

[goldstar]

Flushing isn't necessary. Just drain the oil when its hot as it flows better then and allows a more complete removal of the old oil.

02 DX Millenium Red

 

[billy bronco]

Flushing isn't necessary. Just drain the oil when its hot as it flows better then and allows a more complete removal of the old oil.

Great to here that, this is enough of a pain, I need to be more patient with these things and do right the first time, will I ever learn? Oils are on there way, thanks.

 

[billy bronco]

Flushing isn't necessary. Just drain the oil when its hot as it flows better then and allows a more complete removal of the old oil.

02 DX Millenium Red

Replaced both tranny & rear end fliuds with Red-line, tranny seems to like it, shifts nice & smooth.