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1999 Honda Civic DX Oil leak

My son owns a 1999 Honda Civic DX that deposits a few drops of oil on the ground every evening. There is always motor oil on the bottom of the automatic transmission and it is dripping oil not transmission fluid. When he first bought the car two years ago I was pretty sure that the oil pan gasket is where the car was leaking so I replaced the gasket and torqued all nuts and bolts to the proper setting but it was leaking just as before. There is no visible oil on the top of the engine just around the bottom in the oil pan and transmission area. I’m wondering if anyone has had a similar experience and might have some insight in where the oil could be coming from.

I’m going to guess it’s coming from the main seals, not uncommon in old engines. The seals get old and shrunk and blowby increases crank case pressure.

How many miles does it have on it?

Changing the PCV valve might help, but it’s really just a cheap wild-shot try at fixing what is more likely the effects of age.

It could be the rear main seal, aka crankshaft seal. Not an easy thing to replace.

As the others said, this is more than likely a rear main seal that’s leaking. It happens all the time on older, high mileage cars. Replacing this seal requires removing the transmission, so the preferred alternative is simply to keep an eye on the oil level and add as necessary.

In addition to changing the PCV valve, another “maybe, maybe not” thing to try is switching to a high-mileage motor oil. It’s worth a shot, and a heck of a lot cheaper than pulling the transmission to replace a $15 crank seal.

It has about 108,000 miles on it. I’ve been thinking main seal also but was hoping against hope that someone had a little nugget of wisdom that would point out something simple I might have overlooked. Thanks for the reply!

I like the high mileage motor oil suggestion, I know they put additives in that’s supposed to help seals.

My '89 Accord has been dripping from that area of the engine for years and years. Before I would try the high mileage oil, I’d try a heavier weight motor oil in the warm months. I heard on this site (can’t remember when or who said it) that the additives in the high mileage oils are designed to soften the old seals and gaskets so they can swell-up a little and seal better. Problem is that some seals (apparently, not from personal experience) will soften to the point of disintegration . . . and start to dissolve, causing MORE leaking. My only experience has been not using the high mileage oil but rather using a heavier oil in a high mileage honda . . . 20w50 in Summer. This works well for me, but remember to go back to the lighter weight in the Winter. 20w50 in cold weather will be thick and hard on the starter . . . not flow quickly enough to properly lubricate on start-up . . . and tough on the oil pump. Just my opinion. Rocketman

Thanks for the reply and all the good info. I think we are willing to live with the dripping till it becomes worse. This engine barely uses a quart between oil changes so it’s manageable.

     One quart every oil change?  That's nothing.  108k on the civic?  That's nothing, you'll get many more miles out of it.  GO to a different weight.   Rocketman

I would start with the valve cover gasket. I have a 1998 Civic DX and valve cover gasket seems to seep oil no matter how often I have it replaced. Also, it is almost impossible to remove the oil filter without oil spilling oil. I bet a lot of it comes from there too. Make sure you thoroughly check the mating surface the next time you change the oil filter. Sometimes there can be pieces of rubber left behind from the old filter, especially if you use cheap oil filters or if you get the oil changed at a “Jiffy Lube” type of quick oil change business.

At 108,000 miles, and 11 years old, it’s past time for timing belt change. At this time, be sure to change the front crankshaft seal, and the camshaft seal. It would, also, be an ideal time to change the valve cover seals.

I like your suggestion to change the front crank seal and cam seal with the timing belt change. I unfortunately already changed it several weeks ago and wasn’t even thinking about those two things. The top and the front of the engine are dry as a bone, I’m pretty sure that it’s a rear crank seal or maybe the pan if I didn’t get it sealed up properly.