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trucker 40
04-17-2008 20:09:58
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Re: Oil in reply to Eddie Jones, 04-15-2008 19:27:32
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Along time ago,about 1980,I went to get some barrels of oil,15-40 for diesel tractors.It was Interstate oil in Kansas City.They didnt have any but they said if I went and got lunch they would "make"some.I got back in time to watch them do it.They took a 55 gallon barrel,put oil in it,then poured an additive package about the size of a small orange juice glass in it,put a bung in it,that was it.Someway that made it 15-40. Multigrade oil is just better in my opinion.Straight weight or series 3,when they were used a big truck engine was lucky to last 300,000 miles,many didnt.After multigrade oil we would change bearings at 300,000 and many trucks went 700,000 miles.After a few more improvements,motors ran a million miles in big trucks,as long as they were well maintained.Its just better,and the additives last longer.The old oil would be leaking a lot of times,but burning too.The old motors would be full of sludge like stuff,and black inside.The first motors I tore down with Shell 15-40 in them surprised me of how clean they were inside.There was kind of a struggle for a while to get seals to hold it in,especially in Cat motors,but way back there they solved those problems.As to why its cheaper is its used way more than the other stuff.That is not a real good explanation I know,but its the only reason I can think of.Now what you would even need the old oil for unless you had a real old motor that had always had the old straight weight in it,I dont see why you would need it.Most stuff overhauled since the late 70s or early 80s and especially anything made new since then should be able to use multigrade oil.The main thing you dont want to do is mix them.The multigrade is lighter so it would set on top,and in cold weather the oil pump would draw the thicker oil in first and cause unneeded wear on the bearings.Also if the engine is raced while cold,with the wrong oil in it,it could cavitate the pump and throw a rod.Dont hear of it much,but it can happen.Cavitate the pump means that instead of pulling the cold thick oil in as it should,it pulls a bunch of air because the oil is so thick it doesnt want to go through the intake of the pump and it pulls air instead of oil.That can happen if you put straight weight oil and multigrade together,especially in something like a car,as it has a lot smaller system to pull the oil through than a big diesel motor.I think that the oil being 15 weight when its cold is the big reason the motors last longer with the multigrade.It doesnt cavitate as bad,and the 40 weight when its hot helps it stay on the crank sufaces longer after its shut off.Most of a motors wear comes from starting and stopping and abuse.
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