Since you have been changing oil every 1000 miles, just step up to a 10W40 at the next oil change (same brand)it might help. Stay away from real heavy oils, its hard on the cam and distributor gears, plus your 25000 engine doesn't need it. I run 5W15 in my 250 with just a slight lifter tick after a week or so of setting, as long as it quits in reasonable amount of time, I don't worry about it. You could have a bit of dirt in one of the lifters so a little motor flush or even a quart of ATF right before a change won't hurt. If it gets worse, pull the valve cover and see if everything is still in place. Have someone start the engine while you try and find which one is noisy. It could be just a bad lifter, most new ones are imported in now, so its not unheard of for one out 12 go bad.
The lifter should be able take up any wear on the cam in just a second or two, so I wouldn't worry aboutcam wear to much, you don't have enough spring pressure to really worry about the Zinc levels in the oil. Its the new high lift cams with heavy springs that eating cam lobes.
A really good high Zinc level oil is Brad Penn racing oils. You can find them on the web. Most dyno shops and a few of the cam makers now recommend Brad Penn oil, it has the highest Zinc level out there. It is the old green Kendell oil.
Joe
