Posted by Clint Dixon on Saturday, January 20, 2007 at 11:30:32 :
Jeff, I have seen you asking about using lead additives in a stock L-head 6-cylinder engine. I have been using; first lead additives, and now a lead substitute, in my 230 L-heads since leaded gasoline became unavailable around here. There has been much discussion on this subject here and other forums. Stellite faced valves, valve rotators, sodium filled valves, hard valve seats, and hardened valve seats have all been discussed and the answer to the question of whether lead substitutes actually provide a benefit seems to boil down to a matter of opinion. Some have mentioned that the money spent on lead substitutes would be better put in the bank and saved towards the next engine rebuild. I respect all of these opinions, both pro and con. Personally, I look at using the additives as a cheap insurance.
I ran a few numbers and here is what I found.
I buy lead substitute at $8.50 per bottle (with tax). This is at a farm store where I shop regularly so the cost of my time and mileage to get there can not really be considered. At the recommended dosage it treats 320 gallons per bottle. That equates to a cost of less than 2.7 cents per gallon. I average 10 miles per gallon with my Power-Wagons. That means the lead substitute is costing me 2.7 cents for every 10 miles I drive. Over a distance of 35,000 miles, the total cost in lead substitute to me is $94.50.
I think it was MoparNorm who mentioned here that he felt that a “non-hardened exhaust valve seat will likely last for about 35,000-50,000 miles as is” (without addition of lead substitutes). That is of course assuming that the engine does not have hardened exhaust valve seats, which it should from the factory if it is a T137 original Power-Wagon engine. This is really pretty good longevity from an engine if it is burning non-leaded gasoline and does not have the hardened exhaust valve seats. I don’t argue with that logic. I think that may be reasonable to expect that life span from the valves.
Since before I bought my first Power-Wagon in 1980, I have talked to numerous “old time” owners from years back. They have unanimously reported that the 230 L-head can be expected to last only about 50,000 miles before needing a total rebuild. This was while they were burning leaded gasoline. Valve wear was not really the issue. Cam, rod, and crank bearing were the issue, along with cylinder taper. I have found the 50,000-mile mark to be very realistic the way I use my trucks.
This is where I feel the lead substitute is a form of cheap insurance (for me anyway). If I can get my valves to last past 35,000 miles with spending a little extra money, I figure the engine is going to need a rebuild 20,000 or so miles later anyway. The $94.50 I would have saved by not spending the money on lead substitutes would not go very far towards a valve job at either 35,000 or 50,000 miles.
Cheap insurance in my opinion.
Junior
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