homebrewed semi-synthetics

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Apr 19, 2004
New York
It has been stated on this site that some semi-synthetics are as little as 10% synthetic. Wouldn't you be better off mixing 3 quarts Mobil Drive Clean and 1 1/2 quarts of Mobil 1 (4.5 qt. capacity )so that you know that you have a 33.3% synthetic oil. If this is done what would be a safe OCI? If dino is good for 3K and synthetic is good for 7.5K + would this homebrew be good for 4.5 to 5K. Any thoughts? I assume you should stick to the same brand when mixing.
I guess you can go any ratio you want. I kinda like the packaged oil where it is all blended together from the start. I have used Valvoline Durablend, which their techs tell me is around 30% synthetic. I also use Valvoline Maxlife which the MSDS says is 12-22% synthetic. Want to use some other brand synthetic blend? Call the company and ask them the percentage of synthetic. Of course the off-the-shelf blends probably are a Group III "synthetic," so I suspect there is some added value in blending in a quart or two of Mobil 1 group IV with your dino, or even Redline's group V. [ June 19, 2004, 05:00 PM: Message edited by: TallPaul ]
I ,as, the power players here used to recommend "no blendus oporendi"....but it's your car and since you can get an analysis for under $20, I say blend away. Most oils are fairly compatable....but obviously some logic and restraint are prudent. Soon the 50/50 Pennz LL and Amsoil 15W-40 begins...it sucks beyond belief that the LL no longer has moly. I selected the LL because it HAD moly!!!
[Roll Eyes] Did you get anything in writing about the % synthetic just as he says the the formula with a blend may not be written in stone. But its your car try if wish and let us know how it works out. [I dont know]
Originally posted by Pablo: Soon the 50/50 Pennz LL and Amsoil 15W-40 begins...it sucks beyond belief that the LL no longer has moly. I selected the LL because it HAD moly!!!
So if you haven't begun the test yet, why not use a different long life oil that does have moly in it? How about using Schaeffer 15w40 blend mixed with Amsoil 15w40?? That would be awesome!
Mobil semi-synthetic states that their oil contains 26 percent synthetic. I am VERY leary of semi-synethic oils that do not state the percentages. If is was to go to a mix. I would for instance by 2 quarts of 100 % synthetic and 2 quarts (same manufacture) for a 4 quart system. Then you KNOW you have a 50/50 mix. Ed Hayes
I don't even like mixing grades within a product line, although oil manufacturers say it is ok. Pick an oil and stick with it. If your desire is to mix, you just have not found "your" oil yet.
audi junkie: Perhaps the perfect oil for one's application is not made. Case in point. Through seat of the pants analysis, I am convinced that the optimum viscosity for my honda civic is a 9.0 cst. @ 100 . The only 20 wt I can find that is close is amsoil. at 5.10 plus shipping. So what to do. How about 2.5 qts MC 5w20 and 1.25 qts MC 5w30. That should get it pretty close. Anyway...you see one rationale for mixing. Others may have other reasons like being in control of the amount of synthetic in your blend.
I like blending as straight synthetic can be too expensive, for example my truck takes 3 gallons and due to warranty I can't extend oil changes. But, I also find that synthetic seems to clean better than straight dino, where my first use of a blend fixed what I guess was a sticky lifter on a Taurus. The car had well over 100k miles on it, it was making funny 'chuffing noises' when giving it some throttle, and after driving with the blend for a short while I heard some clicking sounds that got louder and then quit, and then the car drove fine. We have over 170k miles on it now. For the last oil change in my truck I used 3 qts of Mobil 1 Truck & SUV and 9 qts of Delvac 1300, a blend that works well. When I changed the oil in the older Taurus yesterday I used 2 qts of Mobil 1 Truck & SUV and topped it off with what seemed to be 3 qts of Delvac 1300. For the car I was more interested in getting close to a 10W-40, as the Mobil 1 is 5W-40 while the Delvac 1300 is 15W-40. The car has been burning more oil lately so I'm hoping the thicker oil will do better. I'm also hoping that the Delvac/Mobil 1, both of which are a HDEO, will provide even better cleaning. A small consideration is that if it works ok I can narrow my oils to two. But, it's an experiment so we'll see.
I agree with Audi Junkie: I usually go with my oil on the first change and stick with it untill sold which is usually over 150,000 miles. Old habits die hard they say and it one time it was not recomended to keep changing brands due to incompatabilities. I know that todays views are different but, I still stick to one brand of oil out of habit. ed hayes
The reason that I "homebrew" is twofold. 1) I usually have a variety of oils on my shelf.(I can't pass up a good sale on oil) 2) I can't bring myself to go over 4.5K OCI (old habits) and I feel that a full synthetic would be a waste of $$$ at that OCI. I feel that 4 months 4 to 4.5K OCI is fine for my car which is about 75% highway driven but does spend some time in NYC traffic. Sometimes it takes me a half an hour to cross the GWB (George Washington Bridge) when I leave work.
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