Recommendation for a '99 Crown Vic

[Falcon_LS]

Friend of mine has a '99 Crown Victoria with 230,000 km (143,750 miles) on it and has started burning oil due to valve stem seals. This issue was fixed in '96 with 'improved' seals but I suppose it still happens. Then again, his maintenance habits are rubbish.

The oil he used was Motorcraft Synthetic Blend 10w30 every 3,000 miles and adds about a quart every 1,100 miles or so. But the car does see what I would consider excessive idling (city traffic, waiting at the drive thru, etc.) Replacing the valve seals is a true pain in the backside on this vehicle, and before we attempt it, I'm looking at different options.

My first option is to use Kendall GT-1 High Mileage 10w30, which I suppose can be considered 'Motorcraft High Mileage' or Pennzoil High Mileage 10w30. When the oil level starts getting low, top up with MMO one time, which helps swell seals based on that I have read on their forums (despite thinning the oil), and whatever oil we go with next time.

Option two is to go with Liqui-Moly Super Leichtlauf 10W-40, which is a Group III 'synthetic technology' high mileage oil with their Motor Oil Saver (also called Oil Stop Leak). Considering it's now 50+ C (122+ F) outside, I don't think a 40 weight would do much harm.

Unfortunately this pretty much sums up my options as far as high mileage oils go in this market.

But I'm all ears if anybody has other ideas and recommendations. Thanks!

 

[Colt45ws]

I'd try the Kendall or Pennzoil first and if it does not help then go the the Liqui-Moly stuff.

 

[chevrofreak]

Unless you are seeing blue smoke at startup or when taking off from a stop, it probably isn't valve seals. I have a 96 that has been using about 1 quart per 1100-1500 miles, and I've tried high mileage oils and stop leak additives. Since it likely wasn't valve seals, those had no effect. I believe the oil is making it past the pistons, which could indicate dirty piston rings. I would use some Auto RX in a 15w40 diesel oil to make sure the rings are clean. If that doesn't help, try a can of Lubro Moly MoS2 in the oil. It can help fill scratches in the cylinder bore, and is likely why my car has seen a considerable reduction in consumption (1500 miles since adding the MoS2, and my level isn't even down enough for me to add 1/4 of a quart). Though I can't be 100% sure what is doing most of the work, since I started out with 4 quarts of 0W-40 synthetic HDEO and a quart of No Leak.... I did have to add 1/2 quart every 1,200 miles or so for the first 3,000~ miles.

 

[daman]

It probably is valve seals,i've never had luck using High Mileage oil's to combat them seal leaks,time to open her up.

 

[Falcon_LS]

Quick update on the issue. Changed the oil and filter with Kendall GT-1 High Mileage 10w30 and added 300 ml of Motor Oil Saver. The instructions mention 600-800 km (375-500 miles) for it to take effect. So we took the car on a 900 km round road trip to Bahrain over the weekend and back. Oil's been there for 1,280 km (800 miles), it's only used about 200 ml of oil and there's no blue smoke at all.

Replaced the PCV valve, will use Motor Oil Saver for 2-3 oil changes (5,000 miles each) and take it from there.