Use of Additives for Unleaded Gas

[Redwingrobb]

Just curious about something. I currently own an old Barracuda (past 8 years) and am working on a deal for a CS. One thing I've always been curious about is: the effect of using unleaded gas w/out additives, when to use an additive, and what the best additives are. When I first bought my car an ol' timer recommended that I use Marvel Mystery oil and add it to the tank. I've used that and everything seems to be okay. Just wondering if that's a better way to go or if I should just use a lead additive. If I went that way, how often should I use the lead additive..Any thoughts would be helpful..Robb

 

[Russ]

When you rebuild your engine, I would just specify that you want to have hardened valve seats installed. You only need them on the exhaust side, and you will never have to worry about ruining your engine or using any additives. Just my thoughts,

Russ

 

[Redwingrobb]

Crud. I just got the Barracuda's engine rebuilt and didn't have that done. The CS I'm looking at right now has already had an engine rebuild. That being said, what would you use?

 

[68gt390]

Robb;
Like Russ said, if you've got hardened seats on the exhaust side you really don't need to use anything. Most of the additives on the market today will leave a white residue all over your plugs. I used that stuff for awhile and was going through plugs like you wouldn't believe. Most engine builders today when they rebuild an engine put hardened seats in even if you don't ask for them.

Don

 

[Redwingrobb]

So you think I should just stop the Marvel Mystery oil then?

 

[rvrtrash]

I've never liked putting additives in my gas (except Moroso octane booster in my younger days, and fuel injector cleaner in the new cars) so I think I'd skip the Mystery oil. I would call the shop that rebuilt my engine and ask if hardened seats were part of the rebuild, because they should have been. If not, worst case is maybe in 20K miles you burn the seats and valves and add them then.
Steve

 

[Redwingrobb]

I've never liked putting additives in my gas (except Moroso octane booster in my younger days, and fuel injector cleaner in the new cars) so I think I'd skip the Mystery oil. I would call the shop that rebuilt my engine and ask if hardened seats were part of the rebuild, because they should have been. If not, worst case is maybe in 20K miles you burn the seats and valves and add them then.
Steve

I'll ask the shop what they did. Thanks.

 

[Diesel Donna]

I have to use an additive in my old ambulance because nobody has touched that engine since it was born...but the additives for unleaded gas are getting very hard to find. Luckily my CS has hardened valve seats. I'm not crazy about Marvel Mystery Oil....too mysterious.