1991 Other Chevrolet Models lead additive gas usage

Depends on age of gas and if you siphon any debris into drain can.

If gas is over 60 days old, it has begun to degrade and would probably cause more problems than it is worth (varnish).

If gas is under 60 days old, siphon into new or clean container and use a generic filter (3/8" filters are available at most autoparts stores) to filter out any rust particles/debris.

If gas in tank had a fuel stabilizer added to it then you can use it for up to a year (but still filter it).

Thank you for your reply to my question. If I understand you correctly, you are saying to siphon the old gas with a filter as long as it is not too old and has been stabilized. Are you also implying that the off-the-shelf lead additive from the auto parts store will not cause any problems if run through my unleaded vehicle?

You should NEVER use a lead additive in a car designed for unleaded, it will ruin the O2 sensor.

I thought you were asking about the 1976 boat motor.

Automobiles switched to unleaded in the early 1970's, however I am not sure about marine applications, but leaded gasoline virtually dissappeared by the end of the 70's.