Synthetic oil increase consumption - Help!

How much was it using before the switch on conventional, and how much is it using now?

Doc

Before was normal 1 litre every 3k miles, now 1 litre every 300 miles!

Where do I start?

Compression check 1st thing, if that is OK I would replace the valve seals. At this point if it still uses oil I would rebuild.

You have a major leak or a major burning problem! No lubricant change could account for that much of an increase in oil useage.

Valve guide seals or rings, one or the other.

Check real hard for an oil leak, especially at the rear seal. That much oil burning and she'd be spewing blue smoke everywhere.

Doc

Ring stacking? It is possible this happend and it may correct itself in a few hundred to a few thousand miles. You most likely won't see any smoke. You can pull the plugs to see if any of them are oily. How many miles has it been eating oil at the rate?

synthetic oil sucks! has nature ever failed you yet? don't forget: nature made cotton, man made polyester.

Synthetic oil increase consumption - Help! Group: alt.autos.4x4.chevy-trucks Date: Sat, Apr 10, 2004, 1:49pm (EDT+1) From: snipped-for-privacy@NOSPAMeastlink.ca (MZ) I have a '95 3/4 ton extended 4X4 - 5.7 litre - 60k At about 40k, I switched to full synthetic oil. Since then, it seems to be using a lot of oil - every 1000 miles. No signs of leaks and doesn't appear to be burning. Should I switch back to conventional? Thanks in advance.

valve seals DO NOT cause oil consumption, merely a puff of smoke on cold start-up.

Re: Synthetic oil increase consumption - Help! Group: alt.autos.4x4.chevy-trucks Date: Sun, Apr 11, 2004, 12:53am (EDT+4) From: snipped-for-privacy@apexmail.com (Diamond=A0Jim) Compression check 1st thing, if that is OK I would replace the valve seals. At this point if it still uses oil I would rebuild.

Valve stem seals, rings, and a scored bore are the causes of oil burning. Valve stem seals due to the fact that oil runs over the tip of the valve and down the stem and it gets sucked through the guides by the same vacuum that draws the fuel charge in. That oil is a constant supply when the engine is running and because synthetic detergents have probably cleaned the varnish and crud off the top of the keepers and the seals are worn/cracked it just runs down the stem and burns off. Take a look at a 3.0 Mitsu engine after about 40K and you will see just how bad it can get. Damn things smoke like chimneys and burn so much oil you practically need to keep a case in the trunk. Rings could be sticking or worn, easy way to check is a leakdown test.

Steve W.