Mixing oils

WHAT ??

Oil additives typically are a big scam and often do more harm than good.

They are absolutely totally not necessary or desirable in an engine that is in good working condition.

 

I did say case by case

 

I just bought the Mobil-1 5W-30. Doing the change tomorrow. (They also had 0W-30.) It is so damn hot here, I don't think it's going to harm anything. It will probably be 85 degrees on Christmas again. I'll try it for a couple of oil change cycles and see if anything odd happens. I can always go back to the watery 0W-20.

 

Time to be blunt, I guess......since you don't seem to be getting it:

DON'T BE STUPID. Purposely mixing 3 brands of oil and Duralube would be STUPID.
And I bet that Duralube doesn't recommend using it in a 25% concentration either.

Since you seem to have such good results with Duralube.......over such a LONG period of time.......just keep doing what works for you.

Once again, nothing good can come from what you propose, and it might turn out bad.
What exactly do you expect to gain with this witches brew ??
Hint: Nothing.

 

Seriously? You have that much money and time? Send me the money!
600,000 on the honda? mmmm I have no comment on this matter....

Just put ONE BRAND of oil of the correct weight the Toyota calls for and leave it at that.
Then go find something productive and helpful to do to help your fellow man/woman.

 

How many times did you measure and were the trips, temp, miles travel, traffic consistent?

 

I am thinking honey, whiskey, and straight 140 weight.

 

The heck with all this. I'm sticking with 0W20, and change the oil twice a year.

Keep life simple...

 

Go to that website, Bob's the oil guy? You will find him in a Google search. Those fanatics discuss oil 24 hours a day. I think you will get a lot better answers over there.

 

Possibly. I would be concerned about potential chemical reactions within such a stew of slimy synthetics. Might turn to sludge but doubt it. And what Starship16 said.

 

You can mix weights and brands, sure... But if you find the right oil for your conditions, there's no need to mix. Plus, mixing weights is one thing, but mixing additive packages is another. It will be fine most of the time but sometimes mixing 4 different chemistries is not the best option.

I use Redline. 3qts 5w20 and 2qts 0w40. I have very specific reasons why I do this and it starts with my usage. The car is used to commute 115 miles each way to work almost every day. It spends very little time in the start up/warm up phase and the vast majority in the steady state fully saturated hot phase. My climate is the other. In the morning in winter it rarely gets below 38F and in the afternoon leaving work it's typically 100+F in the summer and never below 60F in the winter. Leaving work, 3 miles into my drive, I have a 12 mile climb that requires 1/2 to 3/4 throttle to maintain 60-65mph. It's pretty rough and while I don't have a way of monitoring oil temp, I'm sure it's up there. If oil temp is unregulated (no thermostat), it would surprise many people in how quickly it climbs under throttle and how quickly it drops when coasting/engine off.

With my environment and usage in mind I use Redline with the weights I mentioned. I think it's a safe assumption (someone correct me, please) that the Prius sump temps vary greatly since the engine shuts off a lot and with the constant up and down of my drive, it spends a lot of time under heavy throttle and then engine off.. Oh, and when engine braking in "B", even though the engine may be at a relatively high rpm in a lower "gear" to hold the vehicle speed steady, it's in decel fuel cutoff, the injectors are off. The engine is being driven by the wheels, producing no heat but it's pumping ambient outside air through the cylinders and I imagine the cooling system is still working to a degree so the oil temps drop like a rock in this mode.

My reasons: For one, there are almost zero true synthetics on the market. "Full Synthetic" labels mean nothing. I have to qualify that with this, I consider a group IV and V a true synthetic, not a group III. By law, a group III IS a syn. Everyone knows the lawsuit with Exxon Mobil and how a group III used to not be considered a synthetic. That's not to say a Grp III is not a good oil, there are great oils in that category.

Redline is mostly Grp V Ester base oil. It's a polar oil, it's got a natural cleaning ability even before detergents are added. It has an abnormally high HTHS vs Kv value which can be attributed directly to bearing and cylinder/ring wear, it can take temperatures that most oils can not without leaving itself behind (varnish and deposits, especially in the ring land area), it has a naturally high viscosity index even before the VIIs are added so fewer (if any) VIIs are needed, it resists oxidation, it has a very good NOACK number (the light ends don't burn off, causing thickening over time and far less through the PCV system in the form of vapor) and it tends to remove oxidation which is the reason Redline UOAs don't always look so good. The UOA is not a way to determine engine wear and oxidation removal shows up as wear metals but teardowns of my race car and several daily drivers show wear is almost non existent.

The additive packages are very robust. Lots of ZDDP and Moly. Enough that it can't qualify for an SN rating. On that note, if your Prius is burning oil, Redline is not the oil for you. The high HTHS can definitely help or stop burning depending on why it's burning oil but if this oil gets in the combustion chambers in any significant quantity, your catalytic converters are going to hate you. My Prius has used it for over 40k with no issues and one of my other cars with 147,000 miles on this oil has no converter issues.

People may freak out that I use a 40wt mix in my Prius but it's operated in a hot environment and usually under heavy load for long periods of time. The operating viscosity can easily be as thin as a typical 20wt in a colder environment operating under more normal conditions. If this car were used for just short trips around town, it would have all 0w20 or 5w20 (which would likely be thicker in the sump under those conditions than my 40wt mix is the way I drive mine now). This particular 0w40 has a viscosity index (VI) of nearly 200 which means it thins less at high temps and thickens less at cold temps. With a lesser base stock this could mean more VIIs, resulting in a lower HTHS and more sludge as old VIIs tend to stick around in the form of sludge. This brand is known to have zero VIIs in many weights and very, very little in other weights (the higher the spread, the more likely the VIIs like 0w50 vs 10w30). In really cold temps, it's thinner than many 30wt oils and even some 5w20s.

I think it's best to find the right oil based on your criteria/conditions and stick with it. I choose the brand with the base oil I want and the additive package I want and I mix weights within that brand to get the HTHS I want and still make sure it's plenty thin upon winter cold starts but I may honestly just start using Redline 5w-30 and call it good since I'm in a relatively mild (not cold) climate but with heavy usage. The truth is the engine will likely outlast the car with even the cheapest oil in most cases but it would be nice if it were in great shape, clean, low/no wear, and no oil burning at high mileage.

First post so be easy on me. No time to spell check so I'm sure spelling and grammar are horrible.

The weight of the oil you choose should be determined by ambient conditions and driving conditions.

 

Regarding Duralube, I'm going to look at what it is but many times, these additives are big blobs of viscosity index improvers (VIIs) which is not what you want in your engine. They may quiet it a little or lessen oil burning, but they lower the HTHS and cause sludge. Sure, one or two times isn't the end of the world, but it's not something you want to do. If you're trying to nurse the car along for a few more miles before it goes to the junkyard then use them. It's like a transmission stop leak. I used to rebuild transmissions many, many years ago when I was young, and the stop leak stuff was a seal swelling agent. Autos have many seals besides just the front and rear main seals. The rubber swells up and temporarily stops the leak, but all of the O-rings inside (and there are many) and especially the ones that move back and forth a few mm on a piston with each shift a few disintegrate over a short time and in months and sometimes less you're rebuilding the trans because pressure is leaking by the piston and there's just enough pressure on the clutch pack to slip and burn itself up but not enough to hold and not slip as it's supposed to.

The additive package the oil comes with should be enough. If you're not happy with it, it's time to find another oil, not add extra additives.

I forgot, I'm using Redline D4, not D6 in the trans due to my usage (heat), Motul DOT 5.1 brake fluid, and genuine Toyota coolant in a 20/80 mix, not that anyone cares.

 

You're not going to cause any harm to your car, do track your mileage over the next 5k miles if you're able, am curious how much it changes, I'd bet the number will be unnoticeable to you. I have another 1,200 miles on the current fill of 5w20 before I switch to 5w30.

0w30 would be fine too, if it's the Mobil 1, that's the fuel economy branded oil, which I believe has "friction modifiers" or similar, supposed to lower the parasitic drag on components, thereby increasing fuel economy. But if you're in 85* temp in December, the zero weight is nigh pointless.

 

The only person that may know the results in mixing all those oils would be a chemical engineer that just so happens to work for all the companies at the same time, so has current access to all the formulas. I don’t think such a person exists.....

 

I use redline 0w-20 and my daily commute consists of 4 miles one way to work, average speed 40 mph straight road most of the time, 15 minutes one way. Engine doesn't reach optimal operating temp but I do get about high 70mpg to and 55mph back from work. Do you recommend that I stick to that oil? I'm willing to keep redline in engine if it doesn't burn engine oil, and it hasn't yet. Thanks for your expertise in advance.

 

I would absolutely keep using RL 0w20. I’m just some guy on the internet with an opinion, I’ve heard there are many of us lol, but I have a lot of experience with different oils and teardown results ranging from high mileage daily drivers to my other GN making 1,200 RWHP (~1,500hp the traditional way), (200hp per cylinder for a more meaningful comparison of loads and cylinder pressures.

For the lower average sump temps during short trip use, that 0w20 is easily as thick after 4 miles as a 0w30 after a 15 minute drive down the freeway. That goes for any oil brand.

I know I sound like a RL salesman but I have no affiliation with them and I’m open to others (used Mobil 1 0w40 for a while in my BMW till they went to a lower base stock). What you get with Redline is an HTHS viscosity that’s typically as high as one weight thicker (in Kv). So their 0w20 will behave like a more robust 5w30 when put under pressure in a journal bearing or in a ring pack and won’t temporarily sheer (thin out) while under extreme pressure over and over, sometimes 100 times per second near redline which is not uncommon in a bearing. The other side of this is since it doesn’t temporarily sheer to a lower viscosity when subject to extreme pressure, it causes more drag. This is negligible and is very unlikely to make a measurable difference in power or mpg but it’s something to think I about. I’ve gone from 5w30 to 20w50 and on the dyno it’s within the margin of error.

In the case of a short 4 mile drive where you’re unlikely to see > 160F oil temps, the main advantages are less the high HTHS and more the cleaning properties of the base oil, the lack of deposits over time in the ring land area (the cause of ring sticking and lower power/mpg in high mileage engines, higher moly and ZDDP which lowers sliding friction like ring to cylinder and boundary lubrication in the event of insufficient oil film thickness at startup or in the cam/follower area if not roller, piston to ring, etc), and in the case of hydrodynamic failure in a journal bearing. In addition, you will never have to think of oxidation or thickening because the base oil is that good. Speaking of thickening, with a good NOACK number, it means less vapors through the PCV gumming it up and being burned.

Sorry for being all over the place but I’m on my iPhone and getting dirty looks from the wife and I’m typing as quick as possible. I will be glad to be more specific on anything regarding oil. What I’ve seen consistently is engines so clean internally well past 100k that it looks like you poured clean oil in a new engine that had Been started once. It works well in my 602 rwhp ex daily driver V6 turbo and it has significant advantages in a lower hp regular car. But again, just about any oil with a current rating will help a Prius to make 100,000 and even 200,000 miles. I just believe that based on almost a complete lack of hard part wear (you would not believe what I’ve seen) in high mileage street cars, you can get to high mileage with zero oil burning, insurance should oil temps ever shoot up into the danger zone for conventional oils, and not need to ever run a cleaner in the crank case. Sorry for rambling. Knowing oil temps would actually be the absolute best way to determine what weight to use. A 0w20 in short trip low load operation can easily have the same operational viscosity as a turbo monster on a track running 290F temps. I think I’ve even bored myself to death with this post, sorry.

 

@BuickGN You MUST be a touch typist??

 

The OP is really asking two distinct questions.

To which my answer is, seems like a waste of time, probably creates no advantage, possibly negates benefit to some level. Why would someone think they could make a better end product than the producers of the oil themselves?
I wouldn't bother.

To which my answer is, if the SAE standards are met, and weights are equal, I doubt mixing would cause problems. I personally wouldn't mix synthetics and standard, or High Mileage with Regular.
Lot's of people own, and have owned, myself included, older vehicles that burn oil. When I owned a vehicle that routinely burned oil, I would often top off with different brands of oils. This was mixing different brands. I never perceived it caused any problem.