Hey I've had quite a few problems with transmissions since I swapped my motor. (1990 Civic w/ZC and DX transmission) I already blew one and my current one seems like the synchro for 2nd is bad, it just keeps making a constant jingling noise whenever it is in gear. But it doesn't make sense to me because I bought the transmission off a guy who said it had 100k on it (mabey it did I don't know) and installed it in July 2007. Then I looked in the Haynes repair manual and it said you could use 10W-40 for manual trans axles so I put it in and about 2 months ago thats when the jingling started, prior to this there was no problem especially when it was warm out but living in the northeast it gets real cold in the winter. So I then started to notice that when it was real cold out and just trying to shift from 1st to 2nd or down shift from 3rd to 2nd it was very hard and it seems like there is something keeping it from going in to 2nd. There is no grinding in any of the gears except reverse (sometimes). Today I talked with my friend a Honda tech and he said that that is too heavy of an oil to be running and that for those year cars they usually use 5W-30, but the 10-40 could be why it shifts hard. So I was wondering is 5W-30 the best to use or is there something that is better for the trans axle?