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Rear Main Seal

My 1998 Chevy Cavalier with nearly 142,000 miles has sprung a minor leak. Thing is the leak costs me about a 1/2-quart of oil per week. I’d like to keep this Little Wonder alive and kicking for a while longer and would like to know what the remedy is for such a calamity. I’ve had the valve cover gasket changed, as well as the oil pan gasket (that was a GM dealer’s idea, but the oil still persists after an $800.00 repair–my portion of the bailout is accounted for). What is the fix for a rear main seal on a 2.2L Chevy Cavalier? And, is it really the rear main seal that’s leaking? Thank you for your help.

Before spending the money on the replacement of a rear main seal on an eleven year old car, try one of the higher mileage engine oils such as Valvoline Max Life. These have additives that can recondition seals to reduce or stop oil leakage. Besides, it’s a hell of a lot cheaper!


Thank you for the input. Coincidentally, my local Grease Monkey suggested the same fix. I picked up a quart to keep in the car, per their suggestion, as I go there weekly to get topped off. (They were kind enough to give me a quart, gratis, the last time I was there). Is a 1/2 quart a week a lot of oil to lose? Because that’s what the rate of leakage has been (I put about 600 miles per week on the car).

Thank you, again, for your suggestion.

A 1/2 quart a week leakage on an eleven year old vehicle isn’t much. But the six hundred mile commute each week is also a contributing factor. Your car is a prime candidate for a high mileage oil on this vehicle. Just for yuks and giggles, have those local boys do an oil change to a high mileage oil. You’ll be surprised on the results.


If it is the rear main oil seal, it may have been pushed out by crankcase overpressure. Verify that the crankcase ventilation system (PCV or oil/air separator) isn’t blocked. If it is, pressure builds up in the crankcase that can not be drawn off into the intake air system. High pressure pushes oil seals out.

I have an '88 Supra with 245,000 miles. I’m losing about 1/2 quart per tankful, about 300 miles. I drive about 200 miles a week, so this is about a quart every 3 weeks. This is a slight reduction from a quart a tankful, after replacing front timing cover and cam oil seals when doing the timing belt, and doing the rear main seal when I did a clutch job. The remainder is a combination of valve seals and ring wear.

I think the oil loss is manageable on an 11 year old car. Try the max life oils on the next oil change to see if it will slow things down. It didn’t for me, but those additives do nothing for ring wear.

Thanks for the reply. Those guys actually did suggest that. I thought it was simply a ploy to up the ante for an oil change. However, something told me to trust those guys, and here you are confirming what they did. Again, thank you for the suggestion.

I appreciate your input. I’m not sure if it’s doing anything to slow down the leak, either. But those guys are kind enough to let me show up every week for a “top-off”. I think I’ll consider it to be like owning an old Harley or a classic Porsche. In those cases, they say that, ‘if it ain’t leakin’, it’s out of oil’. I’m going to make every effort to keep that car running, and I appreciate your suggestions.

I don’t want to sound too critical here, but the economics of the problem just don’t justify a repair. A quart of oil every other week at about $2.60 per quart adds up to what? About $70 per year.

The front oil seals usually leak before the rear seals because the oil pump is at the front of the engine. Oil pressure sending units can sometimes leak, they are cheap to replace, but a front or rear seal isn’t justified unless it gets a lot worse or oil gets real expensive.

Have you considered BarryNNJ’s suggestion about the PCV valve? They’re bone simple to check, cheaper than one quart of oil to replace if necessary, and it could be the cause of your oil leak to begin with.

Good point. Economically, it makes sense simply to add oil, rather than have the repair done. It’s just that everywhere I go, I’m leaking oil. Granted, it ain’t the Exxon Valdez, but this is the first car that I’ve owned that’s sprung a leak. (It’s also the first car I’ve owned for this length of time). I agree with your point, though. Thank you for the suggestion.

I am having the exact problem with my 98 cavalier. From the reading I’ve done in my maintenance manual, it sounds like the 98 cavalier does not have a PCV valve, but an ‘oil separator’ instead. The link above to Advance Auto shows a variety of PCV valves, including one for the 98 cavalier model…i guess i am trying to figure out if the 98 has a PCV valve or an oil separator. Any thoughts on this?

PCV valve is usually in the valve cover, or on some V6’s, in the intake manifold between the cylinder heads. It should have a large vacuum line, like 3/8" ID going to or near the throttle body. The check I’ve always used is to remove it from the engine and shake it. If it rattles, it should be fine. I always replace them with every air filter change, generally 2 years, as cheap insurance.