Engine Oil Mixing

[jeffrey]

If I mix 10w30 and 5w30 is it effectively 7.5w30 or do they not mix that way? Obviously I mean the same brand and type.

By the way, this is the best DSM site ever and I have read all of them.

 

[GSX93DSM]

I would prefer you use one type only and the same weight. Is there a reason you are mixing them?

 

[jeffrey]

No reason, besides being nerdy I suppose. I put amsoil 5w30 in this morning. I previously had 10w30 and thought maybe I could gain 10hp or so if I ran a "custom" blend. Ok, so that last part was a joke, I admit.

 

[twicks69]

No, if you mix two different weight oils, it doesn't effectively create a 7.5w30. You would have a mixture of a percentage of two completely different weight oils with different viscosity and thermal characteristics.

You can mix them, since it is just a 5W30 and a 10W30, with no ill effects. I would reccomend that you don't for future use though -- the reason why is that they are already a blended oil -- if you had a SAE 10 and a SAE 30, and put them in a glass -- they would be separated from each other. If you did the same with an amount of 5W30 and 10W30 (with a little red or blue food coloring added), you will see that they will blend--it doesn't mean that it will become a homogeneous mixture though.


Personally, there are a trillion choices for engine oils out there. Synthetics will definitely extend the life of your motor, cylinder head, and turbo. It is done by reducing the amount of coking and residues left behind, having better oxidization stability, high temperature lubrication, foaming prevention and wear prevention. They also have the benefit of going longer without an oil change (even though it is reccomended to replace the filter every 3000 miles or so).

The best synthetic oils are made from a mixture of grade 4 and grade 5 PAO/Polyol Ester mixture with a synthetic base stock. (examples are Redline 10W30, 15W50, etc.)

The best dino oils (conventional) which I have tested so far, is the Valvolvine VR1 15W50 (on my stroker engine with large bearing clearances). Mobil One Synthetic Extended Performance (100% synthetic mixture and base)--( will have the API service label on back with the top saying "API SERVICE SL/CF" and the bottom saying nothing -- it is blank. If it is "energy conserving", do not use it -- it will foul out considerably faster and is NOT a 100% synthetic oil. It may have synthetic mixtures (usually grade 3), but it is using a conventional base stock.


Other excellent brands of synthetic and conventional oils include: Shaeffers, Greddy, Royal Purple, Amsoil, Redline, Mobil 1 Extended Performance, Valvoline VR1 Off Road, etc.

I have used all of these above with Excellent results on a stock motor, and on a stroker race motor. As well, most of the shops I am in contact with, also reccomend the oils listed above with the proper viscosity for your engine's bearing clearances and modifications.



You should use an engine oil weight based on the overall conditions that the engine will see. If that means cold temperatures (less than 30 degrees), or medium driving, I would reccomend a 5W30 or a 10W30. If you are in a warmer climate, maybe you want a 10W50. If you are racing your car with a heavily modified engine under more than 25-30psi, I would reccomend a 15W50(Redline, Shaeffers or Valvoline VR1) or 10W60(greddy).



I hope that my really long post helps, or gives you more information into the physics/chemistry side of oils.

 

[FORMONTOYA]

Actually if you want to get "nerdy"................the number before the "W" is during colder operation............it will flow like a 5 (or 10, etc., whichever the case may be) weight oil, and flow like a 30 weight oil at higher temps.

So, changing the 5W or 10W only effects the lower temp ratings, although I doubt that you created a "special" blend, but that's a different story.

At operational temperature their the same.......30 weight.


And a "nerdy" read from your friends at Advance Auto.....................
http://www.advance-auto.com/english/youcan/html/ccr/ccr20010101ov.html


edit: Damn, I guess my post doesn't mean sh!t after that! ^^

 

[jeffrey]

You answered all my questions better than Google could. Thanks!

For the record, no oil was mixed in the creation of this thread.

 

[Street Surgeon]

Yup, the W doesn't mean "weight" it means "Winter" or displays the viscosity value when it's "cold"

 

[Defiant]

Synthetics will definitely extend the life of your motor, cylinder head, and turbo.

Will they. And by how much? Under Earth conditions, regular oils do as much as an engine needs. If you're in the Arctic, or possibly Arizona (or here last July, for that), synthetics may have a payoff. But I doubt it'll make a measurable difference in engine life. Few run their motors that long anymore.

It is done by reducing the amount of coking and residues left behind, having better oxidization stability, high temperature lubrication, foaming prevention and wear prevention.

True that all those traits are greater in synthetics. However, regular oils aren't pressed anywhere near their limits in automotive engines.

They also have the benefit of going longer without an oil change (even though it is reccomended to replace the filter every 3000 miles or so).

An odd recommendation. Filters become more efficient with mileage. The factory says to change them at every other oil change, and the factory oil change interval is 5,000 miles.
I don't question that synthetics are better. I do question whether they pay off on the street.

And no, don't make up your own oil concoctions.