Factoru oil shearing

[Eddie]

A question occured to me about factory installed oil shearing down. Many of us view a 5w30 oil that shears to a 20 weight as a very very bad thing. My Subaru comes from the factory with a conventional 5w30 oil. I assume that many 1000s of hours on this oil in test engines results in a viscosity recomendation and OCI. From this I can assume that my engine, running on 30 weight oil sheard down to a 20 weight is well protected. We also know that many manufactures are now recomending a 5w20 oil and at least part of the switch is due to much better shear control (base oil + additives). Are we placing too much emphases on only one factor in picking a really good oil for our vehicles. I'd be interested in hearing others views and of course any real data. Thanks Ed

 

[dave1251]

I dont view a oil shearing down to a 5w-20 as a bad thing. Some engine's run real nice on a 20wt oil. Proof is in the used oil analysis. But you need to experment with all weights to see if your engine likes the oil. My truck will run pretty good on a 5w30 that has shear'd down to a 5w-20. But I beleave that it likes a 10w30 better.

 

[Ugly3]

Yes we are. Mobil 1 5w30 was almost a 5w20 out of the jug. How many miles do you suppose have been run on Mobil 1 5w30? Folks here fret over a well made 5w20 like the engine will grenade in 10 minutes. If your engine maker recommends 5w20 just run it.

 

[Triple_Se7en]

The factory oil is for all climates. Your climate is mostly hot. Why not switch to a weight more suitable for your climate & less shearing capabilities.... 10w30?

Substituting a quart or two of dino/conventional for full synthetic to constitute a nice syn-blend will only make it work better in your heat -- plus allow you longer OCIs.

 

[Bill in Utah]

Don't worry about it.

Just change your oil every 6mo or 4-5k (whatever comes first) with a good 5w30 conventional and enjoy the nice ride.

Take care, Bill

 

[radiometer]

Eddie,

I like to use A3/B3 oils for their higher HTHS to provide some protection against excessive shear. I guess the 5W-20s are fine for those who want to use it but I want something better than that.

 

[Eddie]

Yes Triple, I drive in a hot climate and do use a Mobil 1 10w30 oil and a 5,000 mile oci. At 90,000 miles an oil sample sent to Blackstone looked so good that they suggest going to to 6 or 7,000 mile oil change and uoa next time. From other uoa from others it appears that my engine does very well on a light 30 weight or heavy 20 weight synthetic. I like your comment krholm about using an A3/B3 oil but do not fully understand the significance of those rating vs my Mobil 1 SuperSyn oil. Thanks all Ed

 

[mechtech]

Remember that oil viscosity is a RANGE, not an exact value. A heavy 30 may end up as a light 30.

 

[Dave Hess]

quote:

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Mobil 1 5w30 was almost a 5w20 out of the jug

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Is this the GF-3 or the GF-4 formula?

 

[427Z06]

Time to update the mental databases:

code:

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GF-4 M1 5w30 64.8(cSt@40ºC) 11.3 (cSt@100ºC) 3.09 (HTHS Viscosity,mPa·s@150ºC) VI 169

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[brian fix]

Alot has to do with shearing is ,,your PVC valve,,if per chance you have a lube that shears upon a lab check,,and also some engines are harder on oil,climant plays a factor,change times also,condition of engine per fuel dilution,,,,most engine oils on the market shear not that much,, though some are THINNER out of the bottle,,,Schaeffers,Amsoil,Penz Platnum ,work well at staying in grade amoung many brands,,,,,,,,BL