The Camaro Club (UK)
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Mixing oil viscocity
http://classiccamaroclub.mfatw.com/viewtopic.php?f=9&t=5034		 Page 1 of 1
Author:  78 Camaro [Mon Aug 15, 2016 4:57 pm ]
Post subject:  Mixing oil viscocity
Just wondering - what would happen if you took 2.5 litres of 15w50 and 2.5 litres of 10w30 and poured them in (same brand, product line etc. just a viscosity difference). Would you end up with a 12.5w40? or is that not how it works?

I ask because i would like to run 10w30 or 10w40 but the supplier only has those in 1 litre bottles. They do a 15w50 in a 5 litre bottle and it's much cheaper, but don't want to run that heavy of an oil. Have 10w40 in there and the oil pressure is around 50psi at start up and about 40 when running. So was thinking of putting in half and half.
Author:  Jamieg285 [Tue Aug 16, 2016 12:52 pm ]
Post subject:  Re: Mixing oil viscocity
No real life experience or technical knowledge to back it up, but we've had similar discussions on a bike forum regarding mixing of fork oils to get a mid-weight.

The 'wisdom' seems to be that you can mix oils of the same type, but you won't get the logical viscosity, i.e 10w + 15w comes out around 12, not 12.5.

Not sure if the same applies with multigrade oils though, as their properties vary with heat.

Can't you find another supplier that does the oil in the size/price you want?
Author:  sportsroof [Tue Aug 16, 2016 8:14 pm ]
Post subject:  Re: Mixing oil viscocity
No problem mixing oils, we used to mix 50/50 fully synthetic with mineral as per Vizard's recommendation. My take: the wrong oil is better than no oil or not enough oil. More of a concern is the ZDDP content, assuming it's a FT cam. But you already knew that.
Cheers, Martin
Author:  flak monkey [Wed Aug 17, 2016 6:47 am ]
Post subject:  Re: Mixing oil viscocity
Phone Mark at Wasp, he keeps Kendall Liquid Titanium in stock in 5w30, 10w40 and 20w50. Its about £6 per quart... No more expensive than other fully synthetic oils and it has plenty of zddp
Author:  78 Camaro [Wed Aug 17, 2016 11:26 pm ]
Post subject:  Re: Mixing oil viscocity
Thanks for the advice :thumbup:

Sounds ok to mix then, i remember reading something about the viscosity mix ended up not as you would expect i.e. 10 + 15 = 12 instead of 12.5. I realised in my original post i made a typo and put 15-30 whereas it should have been 15-50 (edited the original just now). That probably explains more why i was asking, as 50 and 30 are bit more of a difference than 10 and 15.

Ye, looked into the manufacturers website and they only do 15-50 in 5 litres (£39), everything else is in quarts (£10). It would be cheaper to get the 15-50 and mix in half of 10-30.

Yep - as far as i can tell it's flat tappet (haven't had the rockers / intake off so not 100%). Don't think it's been converted to roller, i would definitely not be stressing a much about the oil if it were a roller :) Working on the assumption it's flat tappet just to be safe.

Have heard of the kendall titanium before, will look into it then if WASP can get hold of it. Sounds quite price friendly in comparison!
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