Are lower HT/HS oils the future?

[buster]

http://webphysics.davidson.edu/faculty/dmb/PY430/Friction/lubrication.htm

With fuel economy becoming increasingly important in today's world, we've seen many oils lower the HT/HS of their product line. (Redline one of the few that hasn't)

I'm curious for some of the engine experts (427/TeeDub etc.)that as time goes on and engines change, we won't need oils with such high HT/HS? The 5w-20's have been a good indicator that we don't need oils with great HT/HS numbers.

If that is the case, and engine design is one reason why we don't, is the other reason due to advancements in additives? Once hydrodynamic lubrication fails, boundary lubrication takes over. This is where additives come in to play.

Look at some of the different racing oils available and how differently they are formulated:

M1 R

ZDDP - 1400/1800ppm
Ca - 3,000ppm
Mo - 60ppm
HT/HS - 3.09

Used in NASCAR with great success.

RL 30wt racing oil

ZDDP - ? High
Moly - 900ppm
Ca - not much detergent
HT/HS - 3.6>

Different applications would require different oils, but it appears that Mobil's approach is relying more on the boundry lubrication if the oil is shearing correct? Where as RL is trying to maintain more of a hydrodynamic film by not having the oil shear at all. Thoughts?

 

[JohnBrowning]

I think that supior material,surface finish's and machinesing accuracy are the future of low HTHS oils. You could not run a low HTHS oil in an engine from 20 years ago and hope for it to last!

 

[Gene K]

I disagree somewhat. There are plenty of 20 year old engines with 200,000+ mi on 5w30. Given the way older 5w30 sheared I seriously doubt it had any better HT/HS in actual engines than 5W-20. I think there are 20 year old engine designs that could survive a 2.4 HT/HS.

 

[427Z06]

I tend to agree with Gene K. SBCs already had roller lifters...and the specific power output was substantially lower 20 years ago. Today, improved manufacturing and designs now leave plenty of margin even in high output engines.

 

[JohnBrowning]

427Z06 wich small block chevy motors 20 years ago came from the OEM with roller lifters or roller rockers? Do you own a small block chevy? If so then give a OTC 5W20 a try and do a used oil analysis? How about your Supra does it have enough used oil analysis to have a good trend going? It might be interesting to see a 5W20 OTC oil in that. I would imagine it would do fairly good seeing how it has an almost bulletproof engine.

Does anyone on this site have a 20 year old chevy small block that they would be willing to run 5W20 OTC oil in?? I would love to see a used oil analysis of one!!!I personely do not belive a flat tappet design from 20 years ago would do well on a SM/GF4 5W20.

 

[427Z06]

In 1987 all SBCs delivered in vehicles had roller lifters. A few other people are already testing 5w20s in older engine designs. For example, I believe Gary Allen is running 5w20 in an older design Jeep engine. Do a search, there are a few posts on this very subject.

 

[Gene K]

John, if you had said 30 years ago I think you may have gotten more agreement about needing a higher HT/HS.

I think both 427Z06 and I were thinking the same thing. I had a picture in my head of a 1987 Aluminum Head L98 350ci Chevrolet in a Corvette and a 1987 5.0 HO EFI Mustang. Both of which use a Hydraulic Roller Cam.

 

[ibewman1141]

My 91 c1500 had a 350 and I believe it used a flat tappet.

 

[Gene K]

The trucks ran flat tappets longer than the Cars. The cars went to the roller when they went to the TBI.

 

[427Z06]

Quote:

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My 91 c1500 had a 350 and I believe it used a flat tappet.

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Really? Maybe the trucks were different. Every reference I have says the SBCs went with roller lifters across the board in 1987.

 

[427Z06]

Quote:

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My 91 c1500 had a 350 and I believe it used a flat tappet.

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Really? Maybe the trucks were different. Every reference I have says the SBCs went with roller lifters across the board in 1987.

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Looks like you are correct. After some checking, I found that some trucks did use flat tappets in 305s and 350s up until 1994.

 

[JohnBrowning]

I was thinking trucks because that is about the only Chevy's I worked on before comeing moveing to Michigan in 1993. I do not recall 1987 Trucks with SBC's haveing roller lifters they were all flat tapet. I could be wrong. I might have to do some research. One problem with 5W20 is that so many people run Redline in off application of 20Wt. that we really do not get a good look at how a 5W20 does inoff application. We need a folder/forume for only off application 5W20 used oil analysis! The search function on this site is not what it used to be and it would make it much easier.

 

[brianl703]

I think Ford recommends 5W20 for the 1993 Mustang 5.0 ... what is the difference between that engine and the one in a 1987 Mustang 5.0 (for which Ford recommends 5W30)?

 

[Patman]

Quote:

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I think Ford recommends 5W20 for the 1993 Mustang 5.0 ... what is the difference between that engine and the one in a 1987 Mustang 5.0 (for which Ford recommends 5W30)?

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The earlier 5.0s got forged pistons while the 93 and newer 5.0s got hypereutectic (or hyperpathetic as some called them)

 

[427Z06]

Forged pistons, while "stronger", generally need more clearance.

http://en.wikipedia.org/wiki/Hypereutectic_piston

 

[Turbodriven]

Most of what is discussed above is to do with HS- High sheer due to the flat tappets etc etc..hope Im correct in saying that?
How does the HT- High Temp bit do with newer motors needing to produce more HP from less fuel thus being leaner burning and running hotter senerio work for the lower HT/HS question?