Who just mixes oils and doesnt care?

[BlueBird]

I posted this question before but it didnt get much response so ill try again here , its kind of related,
What would be the net effect of mixing different oil in respect to the HTHS number ? not worried about the viscosity so much but what would the HTHS number be ?

 

[TC]

For those who missed it the first time...
"It is certainly true that there are additive technologies and synthetics combinations available that could cause incompatibilities." (Shell Oil Co.)
http://www.shell.ca/code/motoring/encyclopedia/motoroil/synthetic_oils.html

 

[Audi Junkie]

I suspect that the reason 30 weight oils tend to be thin is that you are supposed to blend it thicker as desired.

 

[BlueBird]

thanks for the tip but , i was looking for something specific about HTHS number rather than viscosity . That's still good info though.

 

[Last_Z]

quote:

---

Originally posted by BlueBird:
I posted this question before but it didnt get much response so ill try again here , its kind of related,
What would be the net effect of mixing different oil in respect to the HTHS number ? not worried about the viscosity so much but what would the HTHS number be ?

---

I'm no chemist and no insider.....so take my comments for what they are worth!

As far as I can see.........the only negative effect of mixing is that you might weaken the tougher of the 2 oils and/or dilute the additive package of the higher additized oil.

Example......if you mix redline and supertech dino, you will end up with an oil that is tougher than supertech, but not as tough as redline. You will also end up with a package that is better than that of ST, but weaker than RL's

However, this is exaclty why many of us mix oils.....to end up in between at a good price!

 

[rjundi]

We mix in the wife's older car (96 Civic 175,000 miles) constantly. Every oil change dependant on who takes it. My wife favors SuperTech for $12.99 oil change at Walmart with a 5000 mile OCI. I have tried two synthetics Mobil 1 (7500 OCI)/Fram and Valvoline (5500 OCI) both at Walmart. Next I am thinking about Valvoline durablend since the free stuff applies to an oil change place too. I will try to remember to tell them to use a SuperTech filter instead of Fram, we forget.

Its consumption is down now to 1qt/1500 miles which is great, fill has been anything from five year old Havoline in trunk to a half used container of GC.

It should be interesting to see how long it lasts.

 

[TallPaul]

I see a very strong argument for mixing, especially within the same brand:

What if 10w30 is a bit too thin for a particular vehicle and 10w40 is a bit too thick. The 100C viscosity of your favorite brand might be 11 cSt for the 10w30 and 14 cSt for the 10w40. So if you mix 50/50 you should get close to a 12.5 cSt, which is perfect for that vehicle. Sure you probably could get a thick 10w30 off the shelf (Citgo Ultralife 10w30 is 12 cSt) but you really wanted to stick with your favorite brand.

And look at the spread between each grade for 100 C cSt viscosity (taking the middle of each range) from the API chart:

20 wt: 7.5
30 wt: 10.9
40 wt: 14.4
50 wt: 19.1

Man, those are some pretty big jumps. Would you really want to pour in a 50 wt just because a 40 weight was a bit thin for your engine? No way. You would mix to get somewhere in between.

 

[Korean_redneck]

My Tiburon takes 4 quarts of Oil. I'm about to do AUTO_RX..

I will use:

3 quarts of Supertech COnventional and 1/2 quart of leftover low quality, High priced, SL rating BP Motor Oil.

And I don't care cuz they both SL rating.