Is a 5w-20 instead of 0w-20 synthetic? is it safe?
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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.
What does that all mean? The point is that it all depends on where you live. Using something other than the recommended is possible, but I'd recommend discussing it with your mechanic before you choose something different.
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.
What does that all mean? The point is that it all depends on where you live. Using something other than the recommended is possible, but I'd recommend discussing it with your mechanic before you choose something different.
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I've read on other car forums that the biggest difference would be cold starts and in winter (cold areas). The 0 weight will be thinner at startup - less potential wear on parts. That is purely at startup though, as once the oil is warm, the two would basically be identical.
The oil will be too thick on startup to properly protect the parts. Even the 0w is too thick at average cold engine temps. The 0w is to combat it as much as possible and prevent wear.
Would there be much difference after 20,000 or 200,000 miles? I couldn't say.
I'd stick with the 0w-20 full synthetic especially since the Si is a high rpm performance engine.
That said my accord ran to 201,000 on conventional oil before I sold it.
Would there be much difference after 20,000 or 200,000 miles? I couldn't say.
I'd stick with the 0w-20 full synthetic especially since the Si is a high rpm performance engine.
That said my accord ran to 201,000 on conventional oil before I sold it.
EJ8*
Well-Known Member
It's only on start up. In the end when ita fully warmed up the velocity is the same either itr 0w20 or 5w30. Ita only at start up. No it doesn't harm your motor. It wil just kill your gas mileage a bit. I use 5w30 mobil 1 in my car since I bought it. It works no harm. I still get 35mpg in my si on freeway.
boudreaujr
Well-Known Member
Great post. Explained very clearly and now makes sense as to why the Si wants the 0W20 weight. Especially here up north.
Bob-blehead
Well-Known Member
0W-20 is specified in the manual for the non-SI sedan as well. Does that mean I have a high performance engine??? 
Lazaro Ravelo
Active Member
if you live on the surface of the sun (i.e., Miami, FL) like I do, you can get away with using 5w...I see you're in Orlando so you aren't too far off so I think you can get away with it.