best oil for my dad's caddy

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Jan 13, 2003
collierville, TN
My dad normally keeps up with the maintenece and gets the oil done at valvoline every 3K or so.. So im guessing they are using the valvoline dino 10w-30. 10w-30 seems to work for him for weight, is this the best dino.. i dont think he wants to go synthetic due to a possible leak that could develop. The engine is at about 60K miles and is a northstar. He has about 1 quart consumption every 3K miles- which is about average for those suckers.
If he's in the habit of changing oil every 3000mi, then any oil should hold do just fine. It doesn't sound like your gonna talk him into changing. Castrol GTX, Valvoline, and Pennzoil are very good dino oils for his situation. You didn't mention how often those 3K mi changes are. If he is only putting 3000 miles on the car annually and getting the oil changed once a year then you need to get him on an oil that has some stability and has a stable TBN. Such oils would include Amsoil, Mobil 1, and Schaeffer's blend. Whatever oil he uses get him away from the quickie lube places. They are rushed to get through those 15minute oil changes and mistakes happen.
Well the leak thing is a load of crap (especially at only 60k!), but if he's changing every 3k then there's not much advantage to synthetics, I doubt he drives the car hard enough to require the extra protection. Cheers, 3MP
eldawg4100! Nice to see you over here! Check out the "Engine Wear vs. Oil Consumption posts! Got a lot of bbobs statements in there! Most of them are about to get shot down too I fear!
what's so different about the Northstar where synthetics wouldn't work well? I don't drive my Crown VIc (4.6L SOHC V8, not to be confused with the 4.6 Northstar) much, about 3000 miles a year, BUT I do drive the snot out of it. I take care of it though - frequent oil changes, fluid changes, etc...
just a speculation. I am a caddy man myself, and a lot of people with northstars say the synthetics didnt fare to well in their northstar, and dino performed better. But, it works well in the old 4.X pushrod engines.
the owner of Bruce, was talking about it a long time ago. He said M1 worked awesome in his old 92 STS, but not his northstar... maybe it had to do with the DOCH design? yea it sounds outrageous but what he said months ago made sense...
Maybe Dr.T has it right. The M1 synthetics apparently run quite a bit thinner than dino of the same grades. Thinner oil = greater consumption. Of course this is not common knowledge for the general public. Most people will follow the $51,000 car's owners manual to the letter and put in the 10W-30. The other problem seems to arise from higher cost per mile when using synthetics. GM's opinion is that the ONLY advantage that synthetics provide is their excellent high temp. performance. Hence their use in the Corvette engine means that it does not cost GM big bucks to add additional oil cooling! Whereas the Northstar does not run the temp of it's oil very high.
OH yeah, I almost forgot! The design of the Northstar and possibly other GM engines keeps a large amount of oil up in the ring area. this is mostly a direct result of very aggressive surface finish of the cylinder walls. This design insures outstanding ring life if the rings don't stick with carbon or VI improvers. So you gotta drive the heck out of them!
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