Excessive oil consumption, Foird 4.6L engine

[tom/marshall]

I have a 1994 Mercury Grand Marquis, engine has about 98000 miles, runs great, gasoline mileage normal, normal in every way, except oil mileage. If I use 10w-30, as recommended, mileage is about 1000 miles per quart, about 1200+/- miles with 15w-40. Ford says that this level of oil consumption is normal. Car is in excellent condition, with a few exceptions.

1000 miles per quart is unacceptable to me, i'm accustomed to 3000, or more. I know that there was a problem with valve stem seals; if I get these replaced what can I expect. I do not know what the consumption was when new, it was a used car with roughly 70000 miles.

Thank you

 

[BlazerLT]

changed the PCV valve lately?

 

[MONKEYMAN]

I have a friend with a Town Car, same engine, same problem. I found a nice article on replacing the valve seals at the Town Car forum:

http://www.lincolnsonline.com/article40.html

Maybe asking someone there who has changed them may give the info you need on consumption levels. Or maybe at a Marquis forum, if there is one. May not matter. That engine is used in a lot of vehicles/models.

 

[mjo]

The old engine from my Saturn '95 burned a quart every 200-500 miles. It got so bad that I lost track of when to check it and it ran dry. The most recent engine used to burn a quart every 2-3k miles. I installed a Frantz Bypass filter recently and it made a huge difference. Oil burning is gone even when used with regular Castrol. I've noticed it doesn't smell as bad. Running Mobil 1 now still without any leaks or burning. Anyway it might be something to consider given the numerous benefits in addition to saving on new oil.

 

[johnicon]

It's the valve seals. I had a 1993 Grand Marquis with the same problem. Having the valve seals replaced for you will probably run you $500 to $800. You can do it yourself but it's a weekend job for the average DIY-er. I'd have the work done if I were you, since it will prevent/forestall numerous other problems in the future (clogged EGR valve & passages, dirty throttle body, catalytic converter problems, emissions inspection failure, etc.). Good luck.

 

[RF Overlord]

What the others said is correct...Ford changed the valve seal composition somewhere in late '95/early '96 (IIRC) for this very common problem, which usually showed up at right around 100k. If the rest of the car is nice, and you intend keeping it for a while, then do the seals...otherwise it will slowly get worse, but the motor will easily last for another 100k even if you don't do the seals...

BTW, I wouldn't use 15W-40 in a modular motor...you might try one of the "higher mileage" 10W-30 oils...they're generally blended to be a little on the thicker side of 30 when hot, but still maintain the lower viscosity for cold starts.

 

[ULVER]

This has been addressed relentlessly at CrownVic.net : Yes, it's the seals, and it's absolutely normal for that consumption to manifest itself. My 94 Police Interceptor uses about the same. Two things:
1/The "high mileage" oils may buffer the prob, but nothing in a bottle cures the core root of it.

2/The modular 4.6 DOES need oil circulation quickly, or you risk smoking a bearing. You sure the factory called for 10-30, and not FIVE-30

You certainly could get by with 10-30 synthetic, even in cold climates. However, 15-40 conventional oil in a cold winter temps, is asking for trouble.

 

[tom/marshall]

Thanks a bunch guys, particularly Overlord, Johnicon, and Ulver. You have confirmed what I thought I knew already. Re. PCV valve/Blazer, yes the PCV valve has been changed, more than once.

Now I have to decide whether to do it or not.

To answer a couple of other points; Im in Texas, temps below freezing are rare in recent years, I HAVE seen near degrees F in the past.
Also, my manual owners manual recommends 5W-30, but permits 10W-30. I figure that any engine with 100K miles should have enough clearance to get adequate lubrication with a higher viscosity oil, I could be wrong.

T.