Posted by patrick on October 12, 1997 at 20:38:45:
In Reply to: Dumb Questions posted by Gerry Zell on October 12, 1997 at 17:50:36:
Gerry, I don't think 125 miles per quart is "normal" oil consumption for any engine, but it is not necessarily anything to worry about either. If the oil is being sucked past the valve guides and burns cleanly (your plugs don't foul) and you have decent compression, just put in a quart when you stop for gas (who wants to spend more than about an hour and a half at a time in an M-37 anyway?). I have had several heavy truck engines which used oil like this with no apparent damage to any component; just keep an eye on the oil level. If the oil is getting past your rings and you have fouled plugs and heavy combustion chamber deposits and poor compression, then an overhaul is in the works (but still, you can buy a lot of oil for the cost of an overhaul).
I have never had any success with any additive for anything. I use'em occasionally just to see if it makes a difference -- so far, it never has.
I don't see any reason why you can't use a multigrade oil in a Dodge flathead engince. The early multigrades (mid-60s) had problems with polymer breakdowns that caused a loss of viscosity on the "high" rating -- you got a 10-10 instead of a 10-40. I have not heard of those problems for years and most fleet owners spec multi-grade oils for their equipment. The strength of a multi-grade is in dealing with extended temperature differences, and its value depends on the temperature. If you live in a desert and never have to start with crankcase oil below 50 degrees, then a straight weight oil works fine. I live in southern california where the temperature varies from the 30's to the 100s. I run 20w-50 in all my vehicles (2 kick-start only motorcycles, air-cooled VW, old Caddy, Lincoln, 42 WC-53)year round with no problems. In Alaska, a 10w-40 or even 5w-40 might work better. In the Arizona desert, a straight 50 weight might be best.
A more serious issue is detergent vs. non-detergent. A non-detergent oil tends to leave sludge and particles in all the nooks and crannies of the engine, where it doesn't get into the whirly parts. A detergent oil holds the sludge and particles in suspension to be removed by the filter. I have heard that using a detegent oil in an engine which has seen extensive use of non-detergent oils can quickly result in a ruined engine, as the detergent oil picks up the sludge which then overwhelms the filter and then gets into the bearings etc. This may be an old wives tale -- can anyone else out there help? However, unless you've been buying your oil from a specialty outlet which deals in non-detergent oil (it's not real easy to find any more) you're already running detergent oil.