Mixing Delvac or Delo with Mobil1 ?

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May 8, 2003
I'm wondering if one would be safe in mixing 1 or 2 quarts of a detergent oil (for diesels) with 3 or more quarts of Mobil 1 5w-30 for engine cleaning purposes? I have a Toyota truck with the 3.4 V6 with 60000 miles. I have run synthetic for the last 30 thousand. (With K&N filters) I'm not opposed to trying additives like Auto-RX but I'm wondering if occasional use of a detergent oil would produce similar results. FWIW, I have no reason to suspect sludge exists in my engine, I'm just trying to play it safe. Thanks, Greg [Cheers!] [Patriot]
Perfectly fine. Delvac 1 is fully compatible with Mobil 1 and other oils. I'd run a full shot of Delvac 1 and scrap mixing for the next change. [Smile]
All oils, except API-SA, are detergent oil. This concept of whether or not a diesel lube will clean an engine was addressed by Terry a while back. He said that any cleaning would be insignificant. I've worked in some diesel crankcases...no problems, just routine maintenance, and came out black. The good oil protected the engine well, but didn't clean the engine more than needed to avoid deposits. I you don't choose to use Auto-Rx, phone Tim Mills for two or three bottles of Schaeffer #131 Neutra. It works very well and the price is right. Ken
All oils except SA are detergent, but in variying levels typical levels in ppm: SB/CB: 850 SC/CC: 1200 SD/CC: 1600 SE/CC: 1900 SF/CD: 2200 Current diesel oils: >3200 Current gasoline oils: +/- 1000 Switching to a diesel formula will not super clean your engine like AutoRX or something similar, but I've seen it take out a lot of crud.
API-SB is also non-detergent. It does have some additives in it, corrosion and oxidation inhibitors if I recall correctly.
Just buy one bottle of Auto-RX and a spare filter and be done with it. You can us any decent non-synthetic oil for the Auto-Rx application. THis way you will be done cleaning you engine in 500 miles and you will know for a fact that you have cleaned it. This whole diesel oil cleaning an engine out is kind of silly. If oils designed for diesel application were so good at cleaning we would be seeing this advetised as an advatage. Why try to become a backyard chemist with your oils. While I doubt you would ever hurt anything I just as soon know that I am not hurting anything. All oil have detergenccy and none of them have enough to quickly disolve sludge. This would cause catastrophic engine failures as most diesels have some sludge in their pans. I doubt that running delo or delvac is going to do anything that running M1 for the last 30,000 has not already done. The only oil I can think of that might clean better then most would be Redline due to the huge percentage of esters it contains. I would still rather use something like Auto-RX which I am useing right now or Nutra #131 that are designed to gentle clean without damageing your seals.
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