Oil Weight Suggestions? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

LongNLowGMC · 09-29-2013, 03:53 PM

Got a question for you mechanic gurus out there. My truck has just a basic 350 SB, nothing fancy. The previous owner was using synthetic 10W50, and I'm having about zero luck finding this weight oil locally. So since I'm mechanically dumb and have no idea what to use, can anyone suggest another weight oil that would be comparable and maybe a little more readily available / easy to find? Thanks all!

PanelDeland · 09-29-2013, 04:37 PM

10-40 or straight 30 would be my choice.You should be able to find the 10-50 though.Motor oil is rated by weight and 30 weight is a mid viscosity(weight).10-50 would be a 10 weight(viscosity) with the lubricating properties of a 50 weight.That's a very basic explanation and doesn't cover many of the variables.There is a whole "science" petrochemical engineering,devoted to the subject.Most of your LAPS(local auto parts stores) should carry the 10-50 in a couple of brands or more.That along with a good quality oil filter is a basic oil change.
Since you're in a warm climate I would probably use the 30 weight.

1972RedNeck · 09-29-2013, 05:07 PM

15-40 summer, 10-30 winter.

sprint_9 · 09-29-2013, 06:26 PM

Viscosity

Viscosity (a fluid's resistance to flow) is rated at 0° F (represented by the number preceding the "W" [for Winter]) and at 212° F (represented by the second number in the viscosity designation). So 10W-30 oil has less viscosity when cold and hot than does 20W-50. Motor oil thins as it heats and thickens as it cools. So, with the right additives to help it resist thinning too much, an oil can be rated for one viscosity when cold, another when hot. The more resistant it is to thinning, the higher the second number (10W-40 versus 10W-30, for example) and that's good. Within reason, thicker oil generally seals better and maintains a better film of lubrication between moving parts.

At the low-temperature end, oil has to be resistant to thickening so that it flows more easily to all the moving parts in your engine. Also, if the oil is too thick the engine requires more energy to turn the crankshaft, which is partly submerged in a bath of oil. Excessive thickness can make it harder to start the engine, which reduces fuel economy. A 5W oil is typically what's recommended for winter use. However, synthetic oils can be formulated to flow even more easily when cold, so they are able to pass tests that meet the 0W rating.

Once the engine is running, the oil heats up. The second number in the viscosity rating--the "40" in 10W-40, for example--tells you that the oil will stay thicker at high temperatures than one with a lower second number--the "30" in 10W-30, for example. What's really important is that you use the oil viscosity your car's owner's manual recommends.

Read more: How To Pick The Right Motor Oil For Your Car - Popular Mechanics
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I would run 10w40.

09-29-2013, 03:53 PM	#1
LongNLowGMC Registered User Join Date: Oct 2012 Location: Sonora, CA Posts: 134	Oil Weight Suggestions? Got a question for you mechanic gurus out there. My truck has just a basic 350 SB, nothing fancy. The previous owner was using synthetic 10W50, and I'm having about zero luck finding this weight oil locally. So since I'm mechanically dumb and have no idea what to use, can anyone suggest another weight oil that would be comparable and maybe a little more readily available / easy to find? Thanks all! __________________ -Vince- 67 SWB Small Window 70 CST SWB - Long Gone 72 GMC 1500 LWB - Sold

09-29-2013, 04:37 PM	#2
PanelDeland I am a Referee of life. Join Date: Jun 2000 Location: Greensboro N.C. Posts: 13,993	Re: Oil Weight Suggestions? 10-40 or straight 30 would be my choice.You should be able to find the 10-50 though.Motor oil is rated by weight and 30 weight is a mid viscosity(weight).10-50 would be a 10 weight(viscosity) with the lubricating properties of a 50 weight.That's a very basic explanation and doesn't cover many of the variables.There is a whole "science" petrochemical engineering,devoted to the subject.Most of your LAPS(local auto parts stores) should carry the 10-50 in a couple of brands or more.That along with a good quality oil filter is a basic oil change. Since you're in a warm climate I would probably use the 30 weight. __________________ The 47-present Chevrolet and GMC Truck Message Board Network,it's owners,moderators,members,and associates of any type should not be held responsible for my opinion. You can't fix stupid,not even with duct tape. "My appearance is due to the fact that "GOD" does punish you for having too much fun!" Barrett-Jackson has perfected alchemy,they make rust into gold! "You can lead a horse to water but you can't saddle a duck" "Cleverly disguised as a 'Responsible Adult' "Sometimes your Knight in shining armor is just a retard in tinfoil"

09-29-2013, 06:26 PM	#4
sprint_9 Registered User Join Date: Nov 2012 Location: 9 Posts: 862	Re: Oil Weight Suggestions? Viscosity Viscosity (a fluid's resistance to flow) is rated at 0° F (represented by the number preceding the "W" [for Winter]) and at 212° F (represented by the second number in the viscosity designation). So 10W-30 oil has less viscosity when cold and hot than does 20W-50. Motor oil thins as it heats and thickens as it cools. So, with the right additives to help it resist thinning too much, an oil can be rated for one viscosity when cold, another when hot. The more resistant it is to thinning, the higher the second number (10W-40 versus 10W-30, for example) and that's good. Within reason, thicker oil generally seals better and maintains a better film of lubrication between moving parts. At the low-temperature end, oil has to be resistant to thickening so that it flows more easily to all the moving parts in your engine. Also, if the oil is too thick the engine requires more energy to turn the crankshaft, which is partly submerged in a bath of oil. Excessive thickness can make it harder to start the engine, which reduces fuel economy. A 5W oil is typically what's recommended for winter use. However, synthetic oils can be formulated to flow even more easily when cold, so they are able to pass tests that meet the 0W rating. Once the engine is running, the oil heats up. The second number in the viscosity rating--the "40" in 10W-40, for example--tells you that the oil will stay thicker at high temperatures than one with a lower second number--the "30" in 10W-30, for example. What's really important is that you use the oil viscosity your car's owner's manual recommends. Read more: How To Pick The Right Motor Oil For Your Car - Popular Mechanics Follow us: @PopMech on Twitter \| popularmechanics on Facebook Visit us at PopularMechanics.com I would run 10w40.



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