emichura Report post Posted July 31, 2012 I have a Jayco Mini with an 1985 Chevy 5.7 V8 (VIN Code M) engine with 37K miles. The manual calls for leaded fuel. The Light Duty Emission version must burn unleaded -- I assume because it has a catalytic converter. Can I burn unleaded gas in my engine? Are they the same engines with only different emission controls? Do I need to worry about valve seat recession? Share this post Link to post Share on other sites
dickandlois Report post Posted August 1, 2012 Lead was removed from gasoline in 1975. When gasoline was first used, there was no lead in it. Lead was later added as an anti-knock agent. So using unleaded fuel should not be a problem. One can add a little top oil to the fuel to help upper cylinder lubrication and offset the effects of ethanol on the other fuel systems on the engine. Rich. Share this post Link to post Share on other sites
f301359 Report post Posted August 2, 2012 My son has my old 91 Winne/Brave with a 454 chev and two things you need to consider; One, use an octane booster when you gas up or lead additive. This will save the valve seats and be advised that the current motor oils are not necessarily designed for the older engines. So, when you do an oil change add a can of STP or some other oil additive from Lucas etc. This will save a you a lot of problems down the road. Share this post Link to post Share on other sites
