I had an '87 325 BMW with low tension piston rings and it still called for 40 grade oil. 
Thick oils and VVT systems
- Thread starter camrydriver111
- Start date
- Joined
- Jul 11, 2014
- Messages
- 4,118
Shhh... you'll scare away the consensus crowd.I had an '87 325 BMW with lower tension piston rings and it still called for 40 grade oil.
Same with me
FRS asks for 0w20 and I've used euro oil (mostly 0w40/5w40) and of course it runs fine. Going to put Liqui Moly Molygen 5w40 in the Corolla for the winter.
Never knew you could get a Corolla L with a manual. Something we can't get here in the U.S. For '23 the L trim was dropped here.
4WD
$50 site donor 2024
My Pentastar oil pressure (digital) remains exactly the same going from RGT 0W20 to RGT 5W30 …
- Joined
- Mar 19, 2022
- Messages
- 671
Shh don't tell my Honda it has 5w40 in it instead of 5w20. It has been great for the last 2 yrs on 5w30 and 5w40. My Exp and Honda are two examples of 3k oci vs service light and change it when I can PO's. Expedition got 3k oci and is spotless under that valve covers and burn no oil. My Honda was sludged, heavy heavy varnish that even covered the cam lobes and burned a lot of oil. I have been working on it and have gotten burning to stop but varnish is still present over the last 2 years. CAFE is the big push in US, run what oil and oci you are comfortable with.
Another horse beaten to death over the years.
So that doesn’t really indicate anything IRT the grade.
Honestly, I would think the opposite, partially for reasons discussed in MolaKule’s piston ring thread the other day. If we’re talking about sealing, a more viscous fluid will better seal the asperities on the cylinder wall, and higher HTHS will make the oil less likely to separate. I think it’s a win-win, unless all of the tricks of todays machining are used.
IF one were to have the absolute optimal finish, and gapless top rings and Napier second rings, along with gas vents and surface texturing, I could see the thinner oils performing equally to thicker oils. But it’s highly doubtful that anybody’s seen increased oil consumption or PCV trappings by going up in thickness and HTHS. In my mind, everything (albeit limited
) I know about oil says more viscous oil is beneficial, and that as long as the oil flows at startup temp, you could run a straight 60 weight year round if you had a sump heater.Think about it. If you had say olive oil (thin oil) and as an extreme, PlayDoh (thick oil), and you rub your plastic cast-iron pan scraper across your work surface, which one leaves more behind? I’m saying the thinner fluid does. Yes, the example is obviously extreme, but so are the misconceptions that thicker oils pollute the combustion chamber more, IMO.
Possibly, but I do not recall ever seeing the code pop up in the summer months, only in cold winter months.
Specifically, anyone with a GM 5.3 using 5w30 (or heavier) instead of the 0w20 that GM specs? The engine AFM cylinder deactivation system is the only concern I have with using anything other than 0w20. It’s going to be in the 90s here most all summer. 20 weight oil?..
What's the OM or fill cap say to use, 5W-30?
Last edited:
5w-20
Have QSFS Euro 5w40 in my kids 5.3 but don't believe his has AFM
So it's even thrown a P1521 when the specified oil is used?
Yes in winter I use 5-20, I also have a 190 degree thermostat. I commute highway so in winter coolant temp rarely sees 190 or more. The last time I checked (last winter) I had Amsoil Signature 5-20 in there. I also have a tune so that could be an issue.
I have absolutely no concerns about it.
why would it throw the code wth 5w20 though?
