Redline 5w30 v.s 10w-30

Messages
2
Location
MN
I ran redline 10w30 in my LS1 last year, but never 5w30 like GM recommends. I heard that 10w30 was better due to being a little thicker oil, that it would hold up better under high temps. But I did run mobil 5w30, and noticed that my engine ran a little quieter, which everyone said was supposed to happen with 10w 30. What is the difference anyways when hot ? aren't 5w-30 and 10w30 the same then because they have the same viscosity ? I have no idea then why my engine would be quieter with 5w-30. I've also heard GM only recommends 5w-30 for fuel economy, but is that true ? Basically, what I'm asking is since my car is only driven in the summer, would there be ANY benefit of running 10w-30 over 5w-30 ?
 
Messages
450
Location
The Bay Area
Hi-- I don't know if this is true (I'm not an expert), but I heard that the more polymers an oil uses, the more prone to molecular breakdown. The wider viscocity the oil, the more polymers are present. Can anyone varify this? I have a Ford truck and only use Red Line 10W-30 (Ford recommends 5W20). I haven't had any problems whatsoever. [Cool]
 
Messages
267
Location
Rhode Island
If you check the owner's manual, you will find that GM does allow the 10W-30 as long as ambient doesn't drop below 0 degrees. I have been running the Amsoil 5W-30 in my LS-1 without any problems. My UOA is in that section of this forum if you are interested. If you are running Redline, it would be great if you got a UOA on your next change. We need more data on this motor.
 

Al

Messages
19,225
Location
Elizabethtown, Pa
5W oils are much more stabil than they used to be. There is a big difference in 10W oils when you are talking syn and non-syn. With 10W syn you canrun that oil in almost any winter climate because its pumping/pour point is lower than the equivalant non-syn oil. I personally used only 10W-30 Mobil 1 in Pa. I now use the Shaeffers 5W-30 bc they don't carry 10W-30. The reason a 5W oil could be quieter is that it may flow a little better at startup - and also at very temperatures the polymer in 5W may react to be slightly thicker than a 10W oil at the same temp. 10W-30 Mobil seems to hold grade better than 5W-30. Really don't know about Redling. I still prefer the 10W in synthetic. [Smile]
 
Messages
2,077
Location
Cordelia, CA
It all depends on the engine. The only way to really know the differences in YOUR application are to get analysis done on each oil. In my particular aplication, a 300HP LT1 with an oil cooler, 5W30 Mobil 1 does not break down, so there is no need to use 10W30.
 
Messages
922
Location
Ontario , Canada
when you are talking about Redline I don't think the 10w-30 will protect any better than the 5w-30, they all seem to be very stable products. Almost all their oils have the same flash point, pour point and HT/HS numbers, thus you can't go wrong. I say try the 5w-30 for a bit more efficiency and quick start up protection, and maybe hp, but I am sure the differences are very minute. Either would be a good choice.
 
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