Is rotella synth good enough to not need FM adds?

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Staff member
Dec 14, 2002
New Jersey

I curently use delvac 1 almost exclusively, because it is a great oil, and gets me excellent MPG. I have one car that has develloped a few small leaks here and there, but it causes me to seep out at least a quart per 4000 miles. Delvac 1 is a bit expensive to use to top off towards the end of my OCI.

I have liked rotella synth in the past, and although I didnt like it that much in my 98 chevy truck, I am thinking of using it now in the leaky car. My issue is this:

-In this article web page it is stated that rotella synthetic is not friction modified. However, on this board Ive also read that delvac 1 IS friction modified. Perhaps that is why my cars get better mileage with the delvac. So, does rotella have a good enough basestock to not need the FM additives, or are they not added because their target consumer base doesnt need them?

-Do group III oils have any cleaning abilities similar to PAO/esters?

-Does rotella synth have something to make up for the lack of friction modifiers, when in regimes that arent hydrodynamic lubrication? Molakule, n one article, posted that some parts of engines only see hydrodynamic lubrication 40% of the time. Id hate to be relying upon AW adds the rest of the time.

-Why is it sometiems said that HDEO's don't need FM additives? Id think truckers would want to eeek out that last 0.1% fuel economy if they can.

Any advice would be great. I might just start using this oil, since the price is right and its the correct viscosity that I want, etc. However, I dont want to loose 1 MPG, or even 1% of my mileage, because I drive this car a LOT. Obviously fixing the leaks would be the best bet, but at this point I dont have the $600 to do it, nor the time to attempt it myself. So at least I can find a comprable oil to D1, and save $$$ on the topping up of leaked out fluids, and still keep my MPG.


I am unsure of your OCI, but why not add regular inexpensive quality dino (ie Havoline) at the end of your OCI anyway since it will leave soon?

You will have a neglible effect on mileage if any.

[ April 29, 2004, 07:26 AM: Message edited by: andyfish ]
I want to avoid additive clash. Use one oil, top up with it, dont add in anything else (except maybe some 132).

My OCI is 4-5000 as of now; Id like to take it up to 6000, pending my next analysis. Part of the problem is, al the seepage that I get causes me to add a quart+ over 5000 miles. This dilutes the pre-existing oil in there, causing my analysis numbers to be off. So I dont get a real feel of my wear rates.

One word of caution with the Rotella syn- my '87 audi quattro (which I normally run D1300 in) just DRINKS the Rotella. Like, I bought enough for 2 5k intervals but the second jug will have all been added as top-off oil in one 5k interval (!). Seems like that could make your leak worse!

In your situation, I'd add D1300 as top-off if you need it; at least then you're working within one company.


Originally posted by 1maniac:
To be fair to the Rotella-T Synthetic I put it in a '98 Honda 2.0l that was consuming even the newer HM oils and the consumption has stopped all together.

This goes to show that one person's experience with one oil isn't going to be the same with another person's. the oil depends on the application. one brand of oil doesn't fit all!

[ April 29, 2004, 01:05 PM: Message edited by: Cutehumor ]
To be fair to the Rotella-T Synthetic I put it in a '98 Honda 2.0l that was consuming even the newer HM oils and the consumption has stopped all together.
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