Mixing weights

[otis24]

I have about 28 qts. of old formula Havoline 10w30. My current vehicle is spec'd for 5w30. My sump calls for 4.5 qts (4.3 V6). Winter temps are below zero.
I am thinking of running 2qts 10w30 to 2.5 qts 5w30 to use this stash up. Any problems with this?

 

[c3po]

What year is your car and what kind of vehicle, I would use the 10w30 in the spring, summer, and fall, I think the 10w30 would be too cold for the winter months in my opinion.

 

[MGregoir]

Use all 10w30 above 0, all 5w30 below. I think it would be the best compromise.

 

[bmwtechguy]

"too cold" - maybe too viscous?

If you want to do that in the coldest months, consider using it with a 0w30 instead of 5w30. Otherwise, just use the 10w30 straight in the warmer months- no problem since 5w30 and 10W30 are both an SAE 30 at operating temps. In the warmer months the 10w30 will be fine.

 

[otis24]

The vehicle is a 1994 GMC Sonoma (4WD) with 107k miles. I will probably just run the 10w30 in summer and 5w30 in winter.

 

[Drivebelt]

No problem mixing the 2.

10W-30 oils are rated for cold cranking (CCS) at -25C (-13F) -- that's pretty close to about as low as a temperature I would use 10W's before I would want to switch to a 5W.

5W oils are rated at -30C (-22F) for CCS. A mix of 50/50 would put you about in the middle of that. So even if you hit the -F teens, your 50/50 mix should be ok, although a 5W oil would be obviously be preferable for very cold weather. Most of the year I would think that even a 10w30 should be fine in SD.

 

[PT1]

Originally Posted By: otis24
I have about 28 qts. of old formula Havoline 10w30. My current vehicle is spec'd for 5w30. My sump calls for 4.5 qts (4.3 V6). Winter temps are below zero.
I am thinking of running 2qts 10w30 to 2.5 qts 5w30 to use this stash up. Any problems with this?


I do that all the time in my truck. It runs a 7.5w30 and loves it. Now that my 10w30 is gone I have realized a better mpg rate with the 5w30.

 

[sunfire]

Originally Posted By: otis24

I am thinking of running 2qts 10w30 to 2.5 qts 5w30 to use this stash up. Any problems with this?


You have to buy more 5w30 to use your 10w30 stash. By mixing you'll be using up your stash even slower. Use the 10w30 in the spring, summer, and fall (as others suggested) when there is little visc difference between the oils.

 

[twentynine]

Use it that way or 10w in summer and 5w in winter.