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#4536416 - 10/07/17 06:21 PM 2010 paper on extending viscosity grades <20
Shannow Offline

Registered: 12/12/02
Posts: 39864
Loc: 'Stralia

Have posted it back in 2013, but wrong place

2011 viscosity classification task force preso

Of course we know what we ultimately got in J300, this is a part of the road

#4536424 - 10/07/17 06:40 PM Re: 2010 paper on extending viscosity grades <20 [Re: Shannow]
ZeeOSix Offline

Registered: 07/22/10
Posts: 17775
Loc: PNW
Interesting paper. Figure 2a tells me that bearing wear for viscosity below the current minimum of 2.6 mPa.s goes off the cliff with the big step change in the curve. Looks like main bearings aren't as sensitive to low HTHS like rod bearings.

"Additional work demonstrated that a similar step change in wear can be observed in piston ring and cam face wear [7]."

What I don't get however in Figures 2a and 2b is why does the bearing wear increase the other way as the HTHS and MOFT increases? More bearing wear on cold starts with thicker oil possibly? Figure 2a would indicate that xW-20 with HTHS of around 2.5~2.6 gives the least bearing wear.

SAE paper that Figures 2a and 2b references:

#4536443 - 10/07/17 07:04 PM Re: 2010 paper on extending viscosity grades <20 [Re: ZeeOSix]
Shannow Offline

Registered: 12/12/02
Posts: 39864
Loc: 'Stralia
Fair commentary...but then look at 3b, which is more in line with what would be expected.

Engine specifics play a difference, different engines having different issues and behaviours.

This is the link for 3B

interesting comments in the summary...

#4537812 - 10/09/17 10:06 AM Re: 2010 paper on extending viscosity grades <20 [Re: Shannow]
wemay Online   happy

Registered: 04/04/12
Posts: 8885
Loc: Southeast Florida
I wonder if anything has changed since this paper was released. It really questions the decision to use a, recommended by the OEM, xw20 in applications not strictly designed to use it. Like my Sonata.
2017 Hyundai Sonata Sport 2.4L
2013 Hyundai Santa Fe Sport 2.0T