Smoother idle & Smoother Running: My Imagination?

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Aug 10, 2004
High in the Mountains of Central California
I've now been running Rotella-T 5W-40 (and a Wix 51773 humongo filter) in my '83 F250 4x4 with a 460 for two weeks. The engine now idles very smoothly and generally runs very smoothly under all conditions. These are both significant improvements. Could this be my imagination? I have read other posts where posters claimed that their vehicles ran better with different oils, but I have thought that was mainly wishful thinking. Now that I'm noticing a tangible, yet not quantifiable, difference I'm wondering if it is real or imagined... Any thoughts on this?
I would fully agree, find my vehicles running far smoother with way less cold start up noise with Delo 400 which I recently switched from Delvac Super although both are superb oils in their own right.
i have had this feeling in the past too. i think my truck was quieter on delo than it is now on pennz ll when i start it in the mornings.
I switched all vehicles and equipment to Rotella at the beginning of last year. There is no question, all started running smoother immediately. My mileage stayed up and even a little better in each of them.
Big O Dave - - You're not really running ATF in the fuel, are you? You'd have to be at least 65 years old and not have read any recent specs on ATF.
ditto on the ATF i just changed my oil from the pennzoil longlife to the rotella dino 15w40 and can defintaly say that the rotella is much quieter at startup. and oil pressure builds sooner.
Nope, I'm 45 and I read a lot of modern stuff about fuels, oils, etc. And, yes, I AM running MMO/ATF in all of my vehicles, after reading of Gary's experiences. The F250 is finished with the MMO/ATF now, and it is even smoother than it was before. My wife's '95 Explorer is halfway through a tank of MMO/ATF now and you can barely perceive it idling in neutral, a BIG improvement. And, my '76 C20 is also about halfway through a tank of MMO/ATF, and it is running well, too, although it was already running well before. I used the MMO/ATF in it because the intake manifold (an Edelbrock Performer RPM) came warped and I didn't realize it until I noticed that the truck was using a LOT of oil. We finally tracked it down to the intake and I had it machined flat. While it was off, I noticed to my chagrin that there were significant carbon deposits on the intake valves (and presumably in the combustion chambers, as well). So, after bolting the manifold back on, and making sure that the oil usage problem has been fixed, I'm now cleaning the intake valves and combustion chambers. Anyway, I've had no problems whatsover with the MMO/ATF combo; I HAVE had, however, marked improvement in two of my vehicles, the ones with around 100,000 miles on them (the C20 only has 5,500 miles on the engine). Back to the Rotella 5W-40: this is obviously a match made in heaven for the F250. Even before the MMO/ATF, it was MUCH smoother at startup, and as I've done all of these cleaning routines with additives in the fuel, the mileage just keeps improving. My most recent tank was 8.7 mpg, a new high for me with this truck. I hadn't even thought of Rotella 5W-40 until I asked what oil I should use in this truck in this forum, and I followed the suggestions. I am very happy with this oil.
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