5w40 RL vs 10w40 RL

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Feb 20, 2004
Can someone tell me if the additive levels are the same for the 5w40 vs the 10w40? The 10w40 would be perfect for me except the vehicle manuf. specs 5w40.

I suspect that the additive levels in RL 5W-40 and 10W-40 are the same. The only difference is that 5W-40 uses some amount of viscosity index improvers and 10W-40 most likely uses none (or much less than 5W-40). As you might know some VII will shear down, leading to loss of viscosity and other basic properties of oil. Probably RL uses very stable VII, but still... Personally I would pick RL 10W-40 over 5W-40 for sure. If it gets rather cold where you live (below 0F or -20C) I would consider using 5W-40. You might want to try Delvac 1 5W-40. Although I'm not a fan of Castrol, their 5W-40 seems to work fine in Euro engines. Castrol's 10W-40 would be OK as well. If you have a choice Redline, Mobil 1 Delvac 1, and Amsoil are very good candidates.
Hope this helps.

Redline 5W40 does not use polmer thickners at all in the 5W40! Their 5W40 have a HTHS of 4.5 or 4.7! You are not going to get their with VII's! THe 5W40 uses much more expensive base stocks then their 10W40. I used 5W40 for a 6000 mile interval in winter temps from down to -18F and it only used 1/3 of a quart. I often rev past 7000RPM two to three time on my way to work and comeing home from work. If their was any significant usage of VII's of the polymer type I think thei oil would not have held up this well!

To the best of my knoldge Redline does not use any VII's it is all done with base stock blending! Their 5W40 is quickly proveing to be their best product! They do not lisst it though so ask for it specificly!
JB agree with all of that. From the first 5W40 RL UOA here it appeared 'different'. Same price as the 10W40 so if it has more expensive basestocks that explains the lack of advertising. Just went to buy MT-90 at lunchtime and shop had plenty of 10W40 but no 5W40.
I do not have a UOA yet. With that said the 5W40 makes the engien feel like it is frictionless. THe coefient of friction must be incredable low for this oil!

Originally posted by JohnBrowning:
Redline 5W40 does not use polmer thickners at all in the 5W40!

Oops, not true, John, at least according to Dave Granquist at Red Line. He told me in writing that the 5W-40 is RL's only oil to use viscosity-index improver and it uses about as much as dead-dino 5W-30 does.
I know this is the car place...and now I will devulge it is for a motorsackle application. It's for an aircooled guzzi with dry clutch and external starter. It's the new hydraulic lifter motor (non roller) and they have been eating cams. The best info states that there is some dammage at cold start-up. Owners manual states 5w40 synthetic. I want the quikest lifter pump-up and splash to the cam area as soon as possible. That is why I want the best additive package including moly in a 5w40. Thanks to all, Dave PS you guys here give the quickest and most technical responces.
Well I stand corrected. I thought they told me just the oposite but with my swiss chesse memory I must be wrong! THanks for the correction! I am sorry for misleading anyone! It is so shear stable I wounder if Delvac-1 does the same! I would preffer not to have any VII's. That is a lot of VII's if it is on par with a dino 5W30!!! I might have to swithc to their 10W40 or 15W40 for all but winter use!!!

Originally posted by JohnBrowning:
It is so shear stable I wonder if Delvac-1 does the same! I would prefer not to have any VIIs. That is a lot of VIIs if it is on par with a dino 5W30!!! I might have to switch to their 10W-40 or 15W-40 for all but winter use!!!

Interesting...I had sort of decided to use their 10W-40 in the summer instead of their 5W-40, but your note caused me to look again at their specs. The FIVE-W-40 is slightly THICKER at 200dC than the 10W-40 (15.1 v. 14.6), while the 5W's base (40dC) viscosity is only slightly lower at 94 v. 98. (RL's 5W-30's base vis. of 65 is significantly lower than that of the 5W-40.) Obviously the 5-40 uses significantly thicker base stock than does the 5-30. I believe Dave's 'about as much as a dead-dino 5W-30' was oversimplified for me and that it does NOT use much VII. The HT/HS ratings of the 5-40 and 10-40 are virtually identical at 4.6 and 4.7. That 4.6 is 12% higher than that of M1's 5W-40 and 28% higher than that of M1's 0W-40, just another good reason to use RL intead of M1.

I think the 5W-40 will be just fine for me all year 'round. I also think we're splitting hairs here, but as long as I have to buy my engineoil, I'll buy the best I can find.

Dave R, don't be bashful about using the RL 5W-40 rather than the 10W-40; I'm not.

[ March 09, 2004, 02:45 AM: Message edited by: Jeffrey Behr ]
Thanks for all info, I called Dave at RL and he stated the anti-wear package is the same in their 5w40 as in their 10w40. I'm looking for immediate lifter pump-up and spray/splash to the cam area with great barrier film, and viscosity retention at full opperating temp. It looks like RL 5w40 is the best suited based on performance, availability, and price. Thanks again to all.
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