5W30

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truckmandan

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I would not use 30 W oil, but 5w30 or 10w30 or 10w40 should be fine. I have 230,000 on my truck and I use 10w30, but like I said, it never gets cold here. Maybe in the teens for a day or two, once or twice in a ten year period. then it warms up. It also almost never snows here. It may have snowed here 6 times in the last 60 years, and in those 60 years, it may have stuck to the ground 3 times. Also keep this in mind. These engines were built to run conventional oil. synthetic is grate, but will clean so well, that if you have a slow leak, it can get worse with synthetic oil. IMO sythetic oil is grate in an aluminum engine, but in a cast iron block with cast iron heads, conventional oil is fine.
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Thanks. And thanks for the videos. I wasn't gonna use synthetic because of that reason. I'd like to, its just not worth the risk of causing a leak.
 

BubbaGump

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Like everyone has said, it really just depends on how worn the engine is. 5w30 for all year in good condition engines, but you run a heavier oil as the engine bearings wear and clearances open up. Right now I run a 20w50 because the motor is worn slap out, and I might move up to straight 50w if I can find some that's not super expensive. Just keep an eye on your oil pressure gauge. If the oil pressure dips below your liking, and you're sure it's full of oil, you should consider moving up to a thicker oil.
 

jsfrmsj

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Just switched to 10w-40 myself, IMO I should have done this sooner. Oil pressure is a little higher compared to when I ran 5w-30, which is nice. Other than that there is no discernable difference. My truck has 180k btw.
 
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I would not use 30 W oil, but 5w30 or 10w30 or 10w40 should be fine. I have 230,000 on my truck and I use 10w30, but like I said, it never gets cold here. Maybe in the teens for a day or two, once or twice in a ten year period. then it warms up. It also almost never snows here. It may have snowed here 6 times in the last 60 years, and in those 60 years, it may have stuck to the ground 3 times. Also keep this in mind. These engines were built to run conventional oil. synthetic is grate, but will clean so well, that if you have a slow leak, it can get worse with synthetic oil. IMO sythetic oil is grate in an aluminum engine, but in a cast iron block with cast iron heads, conventional oil is fine.
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So let me get this straight, you run conventional oil because you want the extra sludge?
 

kennythewelder

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So let me get this straight, you run conventional oil because you want the extra sludge?
Not all conventional oil sludges. Thats why I use Valvoline. No sludge. Rotella is also good. So is Havoline. Just to mention a few. Like I said before, these engines were designed to run conventional oil. If you do your oil changes regular, like you are supposed to, these engines are good for 350,000 miles plus with conventional oil. As for me personally, I don't want the leaks that I know will happen by switching over to synthetic oil. My rear main has a slight leak now. Not enough to justify pulling the trans, but I don't want to make things worse. Also the added cost of synthetic oil IMO , in my case, is just not worth it. If you like it, them run it. When the day comes that my engine fails, (in about another 100000+ miles) I will see what my options are, but I will be adding a good bit more HP if I still have the truck. I bought this truck in 2002 with 80,000 miles. It has always had conventional oil in it.
 
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90halfton

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It's f###### oil. Run what's recommended by the teams of people that design and test these things for the last hundred years. Use a decent brand and change it regularly
Keep in mind, pressure and flow are inversly proportional. More psi=less flow. Put 200 weight oil in it it'll run 100 psi, for a minute anyway. These dinasaurs don't need to hold 50 psi of oil pressure at an idle, flow is crucial though. Obviously there is a happy medium between the 2.
I'm not a chemist, I just play one on the internet:cheers:
 

redfishsc

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Just stick with 5W30 synthetic, you're not going to improve upon that unless perhaps you live north of Santa.

For what it's worth, I absolutely (and I do mean absolutely) would use synthetic, NOT conventional.

Don't get me wrong, conventional is fine, it will work, but I've converted every engine I've owned since 2004 to synthetic (most at around 180K-220K miles) and have never once gotten a leak because of it. Had a leaky Northstar but it was leaky because it was a Northstar.


Please hear me out on this, if you are in cold weather, and are concerned about viscosity, you're not going to get better lubrication from conventional. Stick with the synthetic. It doesn't lose it's weight (thicker or thinner) the way conventional does over time.
 
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