Hello Everyone....New to this site...hopefully someone can help me out. I bought a used 99 Nomad with about 15K miles on it. I put a few hundred miles on it and changed the oil and now notice oil coming from the plastic gasket type circles on top of the cam towers. I put 10W40 in it...should I go to a heavier oil? Also I changed the plugs (seemed to all be burning the same), the gas filter, cleaned the air filter (It is a thick black hard foam type with no markings on it) and am running Sea Foam through it now...but I am only getting about 25 miles to the gallon and the engine seems to be lugging...like I should be in 4th at 40 for it to run smoothly. Any ideas would be greatly appreciated...does the engine have to be pulled or would a 20w50 oil slow down the leak? Would any type of stop leak hurt or help?