Redline 5w30 v.s 10w-30

Not open for further replies.
Apr 23, 2003
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 ?
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]
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.
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]
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.
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.
Not open for further replies.