Blending 15w-40 + trying to get it to ~10w-30 ?

[Cressida]

I have two gallons of conventional Castrol 15w-40. One is CJ-4/SM and the other is CI-4/SJ.

Since I sold my old vehicle that used it, I wonder if I can blend it 50% with a conventional 5w-20 (like Supertech) so that I can use it up in my old Toyota 5SFE that specs 10w-30 oil ?

Hopefully the additive packages would mesh as well to be good enough for ~5,000 mile change intervals ?

 

[umungus1122]

You could, but you could also just run the 15w-40 straight in the summer. It won't hurt anything.

 

[ccap41]

^ The man's got a good point.

 

[HerrStig]

Yep, I've been running T6 5W40 for years in a couple of Camry I 4s.
Only about 365K on one of them. I suspect that weight is probably accepted in some parts of the world where the nanny state refrains from CAFE type meddling.

 

[Mr Nice]

Any 5w20 oil do just fine to thin it out.

I use 15w40 Delo 400 mixed with 5w20 in an old Honda.

 

[BrocLuno]

How many miles are on your "old Toyota" ? If over a 100K, I'd just run the 15W-40 straight and skip all the bother ...

If you are going to blend, stay within Castrol group ...

 

[Chris142]

I wish you were closer. I'd trade you 10w30 for your 15w40.

 

[Doog]

No need to mix it. Just use it

 

[901Memphis]

There's actually a tool for this that will get it where you need. All you need to know is the KV100 for both. Also works if you have the KV40 for both but easier to find the KV100 on specs sheet.

http://www.widman.biz/English/Calculators/Mixtures.html
Even if you don't know you can set the KV100 in the middle of the grade based off sae j300 and get very close.

I looked up the current Castrol GTX 15w40 and it's a 15.5 KV100 while your average mineral 5w20 will be about 8.5 @ 100ºC
. Interesting enough Castrol formulates their gtx 5w20 right at 9 cSt @100ºC if you want to use that.

Figuring a 50/50 blend of a 8.5 cSt @100ºC 5w20 with your 15w40 you will be at the middle of the 30 grade around 11.4 cSt @100ºC which would be perfect, most likely a well pumping 10w30 at worst.

 

[901Memphis]

Also If you want to use it up faster a blend using 66% of the 15w40 should put you right at the end of the heavy side of 30 grade about 12.5 cSt @100ºC which would be 1 gallon of the 15w40 plus 2 quarts of 5w20.

 

[akela]

I'd mix it 50/50 with 5w30 dyno Supertech. The 100C viscosity will be around 12 cst.

Actually, couple years back, I did exactly this for one OCI. It ran perfectly fine.

 

[SilverC6]

Don't forget a pinch of ginger and a sprig of parsley in the mix.

When I sell a vehicle, I usually hand the new owner a couple of oil filters and any left over oil I have.

Just makes sense.

 

[Shannow]

Per Penzoil commentary above...

Quote:
16. I'm interested in making a custom blend for my vehicles. Preferentially starting with Rotella T6 5W-40, as it's in the family, but wanting something a bit closer to 5W-30. Rotella as it's in the family, and a strong oil, but if needed, Platinum Euro 5W-40 could be considered as a starting point. I would like to blend it down to a 5W-30 using Platinum 5W-20, so that I will end up with a 5W-30 with a little more anti-wear additive than the typical 5W-30. Are there any problems doing this, and will the results be as I expect them to be?

A. The physical results may be very much as you expect i.e. viscosity is likely to be predictable following well known physical laws however the chemical effects are highly unpredictable. Wear performance is not dictated solely by the amount of wear protecting additives in an oil, the efficacy (effectiveness) of the additives must also be considered. Efficacy can be negatively impacted by changing the balance of a formulation package. The approach you suggest could conceivably result in poorer performance, I would recommend choosing a single tier of product, and Pennzoil Platinum has been designed to offer complete protection including unsurpassed wear performance.


Honestly, I don't think that you will have any problems but I would be inclined to run one or the other rather than a mix.