This is for my 1990 Honda Accord. Do I use 5W30 or 10W30? Can I use this for my my car too (Coastal / 1 qt. Dexron III/Mercon Automatic Transmission Fluid)? My car is automatic. Thanks for the help guys.

Also, how often do you have to change your transmission fluid and how many quarts do you have to buy?

 

Definatly DONT use any kind of engine oil in your automatic transmission. If your asking whether or not your ENGINE requires 5w-30 or 10w-30, either would be ok. Generally if your in an area that is hot most of the year, then use 10w-30. If your in an area that gets cold in the winter, use 5w-30 during those times. As far as the transmission is concerned, the Coastal Dextron III/Mercon fluid should not be used in your transmission. Dextron is a fluid designed mainly for GM products, and Mercon for Ford products.

Your best bet would be to go with actual Honda brand auto trans. fluid. Otherise get automatic transmission fluid from your local parts store that says it is compatible with honda, or "most imports". Using the wrong fluids can seriously cause operational or reliability problems.

As far as how much to use depends on what your doing. Im assuming your just doing a "drain and fill". Check your owners manual- it should say how much your transmission requires, as well as exactly which fluid type it needs, and be sure to check the dipstick to be for sure (check the dipstick with the engine/trans at operating temperature, and with the engine running and in "park").

 

According to another post in this forum https://honda-tech.com/forums/honda-accord-1990-2002-2/trans-fluid-2492844/ the above mentioned is the incorrect way to check your transmission fluid level.

 

Yea I believe on certain honda automatic transmission you actually check the level with the engine off. Oh I well I suppose any oil on the stick regardless would be a good sign lol. Honda's just have to be different...

 

The other thing to keep in mind if you're changing the transmission fliud is that you only drain about 2 of the 6 quarts in the transmission (67% of the fluid is still old). To get more of the old fluid out, drain and refill it, drive it around the block, drain and refill again (this leaves about 44% of the old fluid), repeat it again (leaves about 28% of the old fluid). A transmission shop can possibly tap into the cooler lines to make a more complete change all at once.

 

wtf, what do u mean that sounds so incorrect.

 

Just checking the specs tells it all:
For a transmission fluid change you need 2.6 US quarts.
When the tranny is taken apart and re-assembled you need 6.4 US quarts.
(specs are for Accord 4cyl '99)
edit: original numbers were imp. qts, my bad...

 

When I have drained mine, I actually get about 2.5 quarts out. 2.5/6 = 42% new fluid, 58% old fluid. Once it is mixed in the tranny and you drain and fill again, 58% of the mixed fluid is left in the tranny, which includes about 34% of the original old fluid (.58 x .58 = .34). Do it one more time and the portion that is original fluid drops to about 20% (.58 x .58 x .58 = .2). Assuming you only drain 2 quarts each time, the numbers are as in my previous post.

 

yeah where are you getting those numbers and percentages?

 

Assuming Dannyvho has correct numbers (or remotely close) then fleetwood is correct. BTW he worked out most of the math for you in his last post. It makes sence to me... Well I dont understand why you cant get all the fluid out but trannies are pretty complex (especially autos) so I am inclined to believe it. My guess is that all of the parts trap a lot of the fluid. Maybe if you left it for a couple days or weeks all of it would slowly drain? IDK about that part. I do know that when you drain the tranny a substantial amount of fluid is left in the tranny. How much is left? As I remember there was about 2-3 quarts still in it. Anyone ever done a rear main? I have, but it was about 5-6 years ago and I dont remember how much exactly. It was enough to cause quite a mess on the ground for sure.

BTW: That was in a '89 Prelude but it cant be that much different for accords.

 

I have changed the numbers in my previous post: I had used the imp. qts figures in stead of US qts... (data comes from Honda shop manual for the MDJA 4-speed '98-'02).

A lot of automatic transmission fluid is trapped in the torque convertor so you cannot drain all the fluid. For this reason I like to use the Honda recommended ATF (Dexron II or III) to avoid mixing different types of fluid.

 

wouldn't Honda recommended be ATF-Z1? and not dex II or III

I hear these tranny's are fussy, so i only give it the honda genuine stuff, same goes for power steering on these cars...

 

what about prestone?

 

That is correct: following the shop manual's advice is the best thing to do.
For the MJDA 4-speed Dexron is mentioned as an alternative to Honda ATF-Premium. My car had Dexron so I continue using it.
For the MCTA 5-speed in my 2006 Accord only Honda ATF-Z1 is mentioned.