Mixing oils?

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Not sure what to think of this and I apologize if this has been posted but I would like to hear the response from the collective wisdom of BITOG to the following link: linky
 
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I have been an advocate of picking one oil for an engine and using it consistently throughout its life. I know some will say they switch frequently but, I feel this is not the good decision. I sell my vehicles with ~ 125 to 150,000 miles and never an oil related issue. I think the article spells out very well the possible pit-falls of the mixing mindset. Thanks Bigdreama.. Ed
 
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In the days of old maybe it was an issue but not today. Are you talking mixing several brands in one oil change or change brands from oil change to oil change? One of my friends that I change their oil for has 256k miles on their 02 LeSaber and I have used different oils at each oil change since I get what is on sale. I did an oil analysis and it showed good results. This is also at 5k oil change intervals.
 
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My thought is that it is not going to be an issue with motor oil in general. If you are using the right oil Spec'd for your car, brand should not matter.
 
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I suspect this study has little application to motor oil. I have mixed oils all my car's life. It has 151,600 miles on the odometer now. I just drove to Lebec and back to eat at Los Pinos Restaurant. Including side trips, it was about 200 miles in all, on about 8 gallons of gasoline. The car does not smoke & has always passed the smog exam.
 
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Don't all PCMOs say on the back of the bottle that they can be mixed with other motor oils? (other than certain specialized high performance oils; this was mentioned the other day on this site). I change oil brands almost every oil change, and I sometimes mix 2 or 3 oils to fill my sump. It's a great way to use leftovers. My thought is, if there is always some leftover oil in the sump when you change the oil anyway, you are ALWAYS mixing oils to some extent, and this is never a problem.
 
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I mix oils together and change brands often, I have NEVER had problems with my engines. That is not something I started doing when I joined BITOG. I have been doing it for years in many different engines. Oil Co.s' would love you to stick to a brand of oil, why do you think they have you sign up for the ridiculous "warranties" they offer. It increases their profit and there is very little risk on their part since they all have a lot of fine print and they know that the most important thing you can do is change your oil regularly. The chances they would have to pay out is minuscule. Mix Away Chubbs
 
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I do understand why some people have a fear of mixing, based on understandings that "technically" make sense, but in reality, don't. Say oil A has a good, balanced ad pack. Oil B also has a good, balanced ad pack. Separate, they are both perfectly balanced. Now, this is where some would say that if you mix them, it "mixes" or "dilutes" the additives in the entire mixture, rendering the entire combined ad pack less effective, since the new mixture is not the "designed" formulation for either oil. But when you mix oils, even if your total ppm quantities of certain additives are different in a +/- way compared to either the A or B oil, you still make up for that dilution/enrichment of additives. Here's how: Even if a certain ppm quantity of a certain additive in oil A goes down when you mix in oil B, you also introduce new and/or more additives that oil A didn't see before, therefore keeping the entire mixture good and serviceable, just as before. Sorry if that was long-winded, but it makes sense in my crazy mind tongue2
 
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I just changed the oil in my 92 f-350 that I do annual changes and less than 1k miles in that year. I used 3 quarts of Chevron Delo LE 15w40 and 3 quarts of mobile 1 5w20. Should be about a 10w30 based on my math.
 
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It makes me feel better to mix oils with similar add packs but I dont know that mixing a Sodium/Magnesium/Calcium add pack with a Moly/Boron/Calcium add pack really is any less effective. Do whatever makes you rest easier at night as long as its within reason (50,000 mile changes on no name conventional might not be the best idea.).
 
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Originally Posted By: Eddie
I have been an advocate of picking one oil for an engine and using it consistently throughout its life. I know some will say they switch frequently but, I feel this is not the good decision. I sell my vehicles with ~ 125 to 150,000 miles and never an oil related issue. I think the article spells out very well the possible pit-falls of the mixing mindset. Thanks Bigdreama.. Ed
I wouldnt worry about it. I know there is a Mustang 5.0 last I heard was over 700,000 miles on whatever oil was on sale at the parts store.
 
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Of course the consensus of some Oil Companies would be to stay with one brand and never mix oils....not even if the oil is in the same family. I blend oils all the time with no ill effects. I try to stay in the same oil family but that is not always possible. Right now I'm running a gallon of Shell Rotella, T6 blended with 2 quarts of Formula Shell Full Synthetic, 5w-30 and my engine is running smooth and quiet. Why open another Gallon Jug of Rotella T6 for 2 quarts? Why buy 2 make up quarts of T6, for over $6 a quart, when Formula Shell Full Synthetic is a great oil to blend with Shell Rotella T6? Shell Full Synthetic is on sale at BJ's warehouse for $3 a quart in a case of 6 quarts so why the hassle when you can use that case to blend with 3 gallons of T6 for a full sump? Some oils I cant blend in the same family. This is especially true in the case of Chevron Delo. The new SN version of Havoline.....is a big disappointment with the Moly removed. So I will use Formula Shell Dino, SM, to blend with the Delo in the summer time. Unfortunately, Chevron Supreme is not available in my market....but Formula Shell might be a much better oil than CS....and FS is definitely MUCH better than Havoline SN.
 
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big, The link you've provided does not directly address engine oils. However, I tend to agree that mixing oils does not produce an optimal result, and should be avoided in anything not thought of as a beater. I avoid mixing oils in my cars, and I stick to the same oil for at least a few changes in most cases. The people who developed the finished motor oil know more than I do, or does almost anyone else on this site, and the basestock was carefully seleted along with the additive package to provide an oil that meets the applicable SAE grade and API spec to which it was blended, along with any manufacturer's standards claimed. To think that I could produce a superior, or even equivalent, oil by blending oil A with some proportion of oil B is absurd. The claim that all oils are required to be compatible by API spec is okay as far as it goes. I could also mix tap water with a nice Italian mineral water, and still have a potable water, for example. The claim that an engine sounds and feels fine on a given mix is also suspect. You could put one of PQIA's worst performers in your engine, and it would sound and run fine, for at least a while. Mixing may not cause apparent, imediate harm, but I personally avoid it in anything not given terminal beater status.
 
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+1
Originally Posted By: Klutch9
Don't all PCMOs say on the back of the bottle that they can be mixed with other motor oils? (other than certain specialized high performance oils; this was mentioned the other day on this site). I change oil brands almost every oil change, and I sometimes mix 2 or 3 oils to fill my sump. It's a great way to use leftovers. My thought is, if there is always some leftover oil in the sump when you change the oil anyway, you are ALWAYS mixing oils to some extent, and this is never a problem.
 

Ausfahrt

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Thanks for the replies. I realize that the article was from an industrial lubrication publication but I thought that some of the points made could be relevant to automotive lubes. Just some food for thought. coffee
 
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Originally Posted By: lexus114
yeah, and try to collect off one of those warranties....good luck!
Good point. I signed up for the PYB warranty, simply because it doesn't cost anything and what the heck. However, it only allows one claim per vehicle ever and the maximum repair (in Canada at least) is $5,000. It doesn't take much to hit $5,000 these days. If it's something silly and small and cheap and you make a claim, you use up your warranty. If you don't, and nothing else goes wrong, you wasted your time signing up. Oh well. As for mixing, I don't see a problem. I don't play amateur chemist trying to make the best blend. I also prefer to stick with one brand and viscosity per oil change and even over time, but that's just me. I know it's perfectly acceptable to mix oils and I may have to do something down the road to take care of all my orphaned bottles in the garage. I have a bad habit of buying too much oil at each OCI thanks to a history of oil burners and leakers when I was younger.
 
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While mixing different oils might not be optimal, it won't do any harm. If it did, you'd probably see stores separating, say, API SM from SN oils of the same brand, whenever the API switch happens every few years. Like earlier in the year, I was buying oil at the store and saw the same brand, same grade, but the SM stuff was mixed right in with the SN stuff; like every third quart was different. Most people likely don't even pay attention to this - unless they are on BITOG smile - and oil companies know this, and that mixing the two won't cause any harm. I apply the same theory to mixing different brand oils also, whether or not they are both SM, SN, a little of each, etc. The only reason I mix is because after a few OCIs, I end up with extra oil since my car doesn't take an even-quart amount. And I'm not about to waste perfectly good oil bop
 
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