Oil choice

[h20hamelan]

A good article.
I am preparing to change cams, and have some high zinc oil for first run or 500km.
Planning on going back to Shell Rotella T6 5-40 after. Wondering if there is another opinion.

Good article
https://grassrootsmotorsports.com/artic ... tion+Email

[Billmack]

That should be fine. I have been using 15w40 in customer sports cars. As long as hot idle oil pressure stays ok you will be fine with what you have.

[rgh0]

I am not sure that adapting a heavy duty diesel oil such as shell Rotella to a Lotus twin cam is the optimum outcome.

Oil companies spend a lot of time and money developing their oils for the intended applications and I would not second guess them as to the best outcome. I would buy Shells car synthetic range i.e. Helix Ultra rather than Rotella.

In selecting an oil for a twin cam I use the following criteria

1. Use a break in oil from a reputable manufacturer
2. Change to a full synthetic group 4 poly alpha olefin or group 5 polyolester ( or blend of the two from a reputable manufacturer. e.g. Motul, Redline, Mobil, Shell that suits the application be it road, track day / road or full race. Race oils tend to have less dispersant and other related additives as they focus on lubrication rather than service life
3. The lower viscosity you can use, the better, in terms of power output and oil cooling flow to the bearings. Unfortunately oil pressure is not a good measure of whether you can go to a lower viscosity oil as its all about the hydrodynamic film strength versus bearing dimensions and loads. I suspect a twin cam can happily run on a modern synthetic 5W / 40 or 5W / 30 provided the clearances are in spec. But I stick to 10W / 50 as I cant afford to do the development testing with lower viscosity oils It probably means I am loosing a little HP but rebuilds are expensive also

cheers
Rohan

[TBG]

I use this. My engine builder says use the most advanced oil you can get. They spend millions on getting it right.

Valvoline VR1 20w/50 Racing Oil 5 Litres
High zinc / phosphorus provides extreme wear protection, including flat tappet applications
Additional friction modfiers to help deliver maximum horsepower
Enhanced anti-foam system protects engine during extreme stress
Compatible with gasoline or alcohol fuels

[TBG]

I use this. My engine builder says use the most advanced oil you can get. They spend millions on getting it right.

Valvoline VR1 20w/50 Racing Oil 5 Litres
High zinc / phosphorus provides extreme wear protection, including flat tappet applications
Additional friction modfiers to help deliver maximum horsepower
Enhanced anti-foam system protects engine during extreme stress
Compatible with gasoline or alcohol fuels

[LaikaTheDog]

Heard good things about this oil on another forum, but I cannot find the discussion to link it for you

Millers Oils NANODRIVE CFS 5w-40 Fully Synthetic Engine Oil

Apparently recommend for "chocolate Porsche engines"

Think I will change oil and filter on my esprit before a track day and see how it performs.

[The Veg]

As a semi-interesting tangent, Rotella is well-established as a great alternative in air-cooled BMW boxer-twin motorcycle engines from 1969-95, which had flat tappets and pushrods. These engines were originally specified for 20W50 and had dry clutches so a standard motorcycle oil wasn’t needed. Those old BMWs are generally reliable-enough that people still ride them long distances and into places where oil choices may be limited, and they’re easy and cheep to rebuild so a few adventurous souls had no problem doing the R&D over the years.

But just to be clear, that doesn’t mean it’s a good idea to use it in your Twin Cam.

[Billmack]

I have had good results with Rotella as it seem to be kind to flat tappets. My dyno tester is a fan of the VR1 so we generally break in and power test with that. No doubt about less viscosity gives more HP but we shortened the engine life from what I saw. We used 5 weight at big tracks where power is rewarded but did rebuild afterward.