Just bought up an 86 Nissan Hardbody pickup. 3.0 V6 with high miles. Runs really well and started right up after sitting for over a year, no smoke or anything. Has a slight tap in the top end after running for about 10 minutes but I figure that may also be because of sitting so long. Speedometer doesn't work so not sure how many miles are on it. It seems to have quit at 178k so I assume it has well over 200k on it. Was running hot since the fan clutch does not seem to do much. Will try to replace the basic items such as the fan clutch, thermostat, speedo cable and leaky valve cover gasket. Just wondering what is a good oil to clean it out without putting many miles on it since I prob will not drive it much. Just keeping it around for runs to Home Depot and such. Have just about any oil in my stash at this point but I am thinking synth may not be a good idea since it is old and most of the gaskets are at least seeping at this point. The recommended weight is 10w40 with 10w30 usable below 50 degrees or so. The oil in it currently is not really that dirty but obviously could use a change. Black coating between cam lobes but not sludge goop just looks like someone spray painted it black. Can still see the texture on the cam surface between the lobes. So it is not all sludged up it seems.