Great To Be Alive

If Honda wants us to check the oil level of both the differential and the transmission with the vehicle at normal operating temperature, wouldn't a fluid change where you put in cold fluid result in a slight overfill. Yeah, I know silly to even think about it as it's probably splitting hairs... but in the manual they specifically state to check both at normal operating temp. Just seems odd, especially given that some members intentionally overfill the tranny. Even when it's done to spec, if the fluid is cold, it will be inherantly overfilled slightly from spec.

My other post on Symptom / Cause of a 2nd gear pop out / miss shift got me to thinking about it. Too much time on my hands...

zeroptzero

Once I put the fluid in I never check the level until the next time it gets drained. If I fill the tranny and diff till it flows out of the fill hole I won't check it again unless I see signs of leakage. I'm on a change interval of once per year for both tranny and diff. I say fill the tranny and diff cases and just check for leakage every couple months. I put all my fluids in at room temperatures, in the winter months heat them up in the house before pouring in the vehicle.

The raising of the fluid when hot will do more good than harm, and it is pretty small in terms of overall fluid level either way. I wouldn't want to check it fully warm as then it would flow out of the fill hole and once cool it will be below the fill hole, so I perfer to not check the fluid level either way.

irv_usc

how do you check the fluid level in the diff?

Great To Be Alive

Well... that's my point. If you check the fluid level when the vehicle is at normal operating temperature, fluid will flow out... then the fluid level will be below the fill hole when cold. But that is Honda's intent... as they specifically state to check both transmission and differential when at normal operating temp. It just means that when doing a fluid change and adding cold fluid until it runs out the fill hole... it will result in more fluid than Honda specs. Your way of warming the fluid results in less overfill, though.

The DIY on this forum calls for adding fluid until it runs out the fill hole when changing fluid. Anyone have a service manual handy to see if it describes adding fluid until it runs out... or just adding the proper 1.6qts or .8qts quantity for trans and diff respectively. Just curious...

Great To Be Alive

Manual describes the same procedure as for the trans. At normal operating temp, with the vehicle on level ground, remove the fill bolt and feel for the oil level being at the bottom of the fill hole. Again, this is at normal operating temp, when the fluid has expanded... hence my original question.

rob-2

I believe you'll find the tolerances greater than expansion of the fluid at temp.

zeroptzero

fill the sumps at any temp, put in fluid that is around 70 degrees (room temperature), fill both sumps till you see fluid pour out of the bottom of the fill hole. Once the fluid stops dripping out, close up the fill bolts. If you choose to check them again check them when the vehicle is cold and the fluid level should be close to the bottom of the fill bolt again and you will get minimal fluid leaking out. But again checking the fluid is useless unless you have a leak, which would be very noticeable. I won't waste my time checking the fluid level when I know that I've filled it to the proper level and I can see that I don't have leaks.

Filling to the bottom of the fill hole is more accurate than trying to measure out the prescribed amount IMO, I feel safer doing it this way and it's how most people do it. I've done it this way on dozens of cars, you can't overfill or underfill it this way. The expansion of fluid at temperature is a non-issue unless you choose to open the fill bolt when it's hot, which I don't advise.

Disregard Honda's suggestion to check the fluid hot, it just causes confusion for people that aren't use to servicing tranny's and diffs'. That suggestion is more applicable to automatic transmissions which we don't have. Fill it cold and check it cold ( if you desire to even check it at all) and dont' stress over it. The only way you can mess it up this way is if the car is not level when you do the servicing. I put my car up on jackstands and check it with a level just to be sure when I do it as my garage seems to have a bit of a slope to it, lol.

hth.

Saki GT

I agree - fill until it starts to pour back out, cap it up.

Great To Be Alive

Yeah, that's what starting me to even question the whole hot vs. cold level. I just changed both fluids and am now realiziing my garage isn't as level as I thought and I had the vehicle intentially oriented to slightly overfill rather than underfill if anything. I was surprised to see the slope when checking with a good quality level (turns out my other level is way off). All the feedback (which I very much appreciate BTW) of "Overfill isn't any problem at all, it's probably good" ... is fine, I just like to do things by the book. So I will be rechecking levels and thought I may as well follow Honda's specification.

I have come to my own gut feeling conclusion that overfilling is just as bad as underfilling when it comes to the trans. This based on some seat of the pants evaluations of how the gearbox felt after the fluid change.

zeroptzero

you can usually tell if something is wrong when overfilling. If the diff takes about .8 quarts and it isn't leaking out after 1 quart you know it isn't level, but the extra .2 quarts wont' hurt it and you don't go into a second bottle. I think the tranny takes 1.8 quarts, if it doesnt' leak out at 2 quarts then you know it is overfilled, yet the extra bit .2 quarts won't hurt and you don't go into a 3rd bottle.
I think it is pretty foolproof based on the quantities that are needed.

I know other manual trannies on my cars were vented if you overfilled it the vent leaked and that is when the tranny begins to feel worse. You really need to go crazy to get it to that point though, like 1 full quart over.