Ultimate gas mix???

[John in Ct]

In my 154 Cub Lo-Boy ( Non- hardened Valve seats) I have been running high test gas( as per manual) mixed with Marvel Mystery oil( 1 oz to 2 1/2 gallons of gas) and VS+Lead Substitute (5 0z to 20 gallons of gas, I got a case for free !!). Now I am reading about Sea Foam on these sites and see it in the stores here so it got me thinking of using it in my gas in addition to or maybe instead of what I have been using. The Sea Foam can I think said 1 oz Sea Foam to 1 Gallon of gas for maintaining and 2 oz Sea Foam to 1 Gallon of gas for stabilizing+ cleaning. So I guess my question is to find the ultimate mix ( and ratio's) of additives ( Marvel Mystery oil, a lead additive, Sea Foam or none of the above) to put in our gas that would protect our Cub's Valve seats and lube the upper cylinders and maybe do other benificial things. Cost isn't an issue because of the low hours I put on my 154. Thanks!!

[Jack Donovan]

I agree with you, Others don't. I am a firm believer in putting some led in the fuel of these old machines. How you do it is up to you. I have used Marvil oil for years. And for lead I use to dump in a half a cup of diesel . Now thats out because of Bio. sea foam is great for keeping everything lubed and clean as well as releasing lead carbin out the exhaust. I'm sure I'll be going to some sort of led addetive and stable in the winter as well as the others. For what it is worth. Jack

[Eugene]

Regular gasoline here, 87 octane. Cub's do not require a high octane fuel.

During the mowing season. No additives to the fuel. Stabil in the fuel for semi-winter storage.

Sea-Foam. I use a bit in my tractors with very old engines to help keep the rings and valves free.

Lead additive. Waste of money.

My opinions.

[Jim Becker]

The 154 manual calls for 90 research or 84 motor octane. Gas pumps are labeled with the average (87!).

I use Sta-bil because I never know how long it will be sitting in the tank. Sea-Foam reprtedly will do the same. I don't add anything else as it is just burning money.

[George Willer]

The Cub was built to run on 80 octane gas without any consumer additives. Seafoam and Marvel Mystery Oil are intended to be used to correct problems on poorly maintained engines. Unless your engine is messed up from sitting for very long periods or a malfunctioning carburetor the only thing higher octane gas or additives can do is "feel good" for the owner. Keep in mind that some additives can be counterproductive by adding to cylinder deposits.

It's up to you to decide if the possible benefit of additives is worth it to you.

[KETCHAM]

I run regular in mine.Additives when I get them free at work.Bike I run 87 to the 70s.when the temps go up so does the gas.Kevin ps I have not heard my cub ping yet!!

[jimbaker]

I'll add my .02... sure, cubs were made to run on 80 octane fuel, but the fuel was leaded at the time...TEL, (lead) was added to gasoline for upper end (valve) lubrication, but was removed in the late 70's early 80's for environmental concerns.
Typically speaking, the octane rating relates more to timing issues, such as detonation, than it does to lubrication. As previously posted, octane ratings are calculated by r+m/2 method, which means a research engine was ran and the timing advanced (or retarded) to the point of detonation, and this value was compared to a calculated point where detonation should have occured, and the average of these 2 figures is used in the determination of calculating the octane rating.
Marvel mystery oil and other additives are sold as a lubricant, to aid in valve and guide lubrication, not as an octane booster. The drier, modern fuels lack the lubrication properties of the old fuels containing lead.
So, in my opinion, use good gas without ethanol (ethanol makes the fuel even drier), dont worry about high octane ratings, and use the mystery oil because it ends any lubrication problems with the valves.
We have the same problem in radial aircraft engines.

[c172skyhawk2]

i will run normal car gas gas through mine during the warm months. For the winter time a occasionally in the summer i will burn aviation fuel (100LL, 100 octane and low lead) it is a really clean burning fuel and is leaded to lube the top end it has a really good stabilizer in it already so i don't have to fool with that, but most of the time is car gas.

[Lurker Carl]

I'll add my .02... sure, cubs were made to run on 80 octane fuel, but the fuel was leaded at the time...TEL, (lead) was added to gasoline for upper end (valve) lubrication, but was removed in the late 70's early 80's for environmental concerns.

80 octane fuel was unleaded, that's the reason for it's low octane rating. It was the cheapest fuel available so most dirt poor farmers who could afford a Cub would use it.

Tetraethyl lead was added to gasoline to increase octane so higher compression engines could be mass produced and used without detonation issues. Alcohol is now used to increase octane.

Lead is NOT a valve lubricant. This myth started when lean burning engines (requiring unleaded gas) had problems with burned valves. The problems were due to the increase combustion chamber temperatures and lousy valve/seat materials.

[George Willer]

80 octane fuel was unleaded, that's the reason for it's low octane rating. It was the cheapest fuel available so most dirt poor farmers who could afford a Cub would use it.

Tetraethyl lead was added to gasoline to increase octane so higher compression engines could be mass produced and used without detonation issues. Alcohol is now used to increase octane.

Right! In those times there were 2 grades of gas... Regular and Ethyl.
Ethyl was for higher compression engines and was named for the tetraethyl lead that was added to the same gas to raise the octane level. Regular like the Cub was intended to use was unleaded.

[jimbaker]

In the 40's, TEL was present in ALL gasoline, reguardless of it's octane rating. It (TEL) was patented in the early 20's as an octane booster, and was used until banned entirely for automotive use in the US, I think in 1995. TEL is still used in the production of aviation gasoline.
Throughout the 1930's, as unbelievable as it sounds, automotive gasoline had an octane rating of around 40, and aviation fuels had an octane rating of 75-80. With the use of TEL, they were able to get the octane up to around 87 for automotive use. "Cracking", a refining term, was used to further boost octane, and resulted in 100 low lead aviation gasoline, which was lower in TEL than the 100 octane and 80-87 aviation gasoline. WWII needs for a higher octane fuel was the driving force behind that breakthrough.
The benefits of TEL as a lubricant to valves and valve components are very well documented, as is the damage to engines designed to use it not having it. Most engines of that era did not have the advantage of having hardened valve seats, which were unnecessary due to the leads lubricating properties. In an unmodified state, these engines suffered from unleaded gasoline available subsequent to the ban on TEL which is again well documented and probably most apparent on aircraft engines. Approvals to run aircraft on automotive fuels still recommend occasional use of aviation gasoline, because it still contains the TEL necessary to lubricate the valve seat and stem areas.
As far as 80 being cheaper than high test, sure it was... the 80 was lower on the distillation chain, and did not go through the catalyst cracking process required for the higher octane fuel. I was not around then (the 40's and 50's), but I do remember the phase out of leaded gas... where it was marketed to be cheaper because of the lack of lead.
Lastly, I'll stick to my guns and say buy a good quality of gasoline and add your choice of top end lubricants, because however you stack it, todays fuels lack the lubrication properties of fuels produced in the past.

[Jeff M]

Great discussion. I've had my Loboy for 4 years, and I've reason to believe it was a low time tractor when I got it. I've run 87 in it, no additives, mowing 3 acres weekly and doing some snowplowing. It would seem to me that at this point valve damage would begin to show itself, but hasn't. It still runs clock-smooth, no skipping or popping. Guess I'll stick to the original game plan for now.

[Bus Driver]

http://en.wikipedia.org/wiki/Amoco For some of the history of unleaded gasoline, this link should help. Amoco is now part of BP. Amoco premium gasoline, their highest octane, was and always has been, unleaded.

[BigBill]

My buddy in the equipment/repair business told me to use nothing but high test in all my equipment. The gas is garbage nowadays after all were burning corn liquor aren't we?

I run high test and use seafoam thats it except the occasional two stroke i add. My 154 loves the upper lube from it. Seafoam does that too.

The govenor runs smoother on high test.

[moe1942]

Putting premium fuel in a Cub engine is wasting money. I agree with the thinking that regular is all it needs. The only additive I use is Sta-Bil because gas starts degrading after three weeks.

But if one thinks that it is better to use premium then I say go for it. I'm just registering my opinion..