I use Millers 5-40 full synthitic oil:
CFS 5w40
DESCRIPTION:
Competition full synthetic engine oil.
Formulated with 100% synthetic base fluids, including a synergistic blend of three esters combined with the latest additive technology for maximum performance.
APPLICATION:
Use as received for competition or modified engines where maximum power release is the preferred criteria.
Formulated for high revving engines used in circuit racing or for larger engines for short duration i.e. hill climbs and sprints.
USER BENEFITS:
• Fully synthetic oils provide many outstanding performance benefits over conventional mineral oil.
• By utilising both polyalphaolefins (PAO) and ester synthetics specially selected to minimise the amount of polymer used, the lubricant film provided is more resistant to ‘shear’ and viscosity loss in highly stress areas.
Full synthetic oil provides:
• Load carrying capacity many times that of mineral oil.
• High film strength for ultimate protection.
• Outstanding cold flow properties for reduced wear at start up.
• Excellent thermal stability and oxidation resistance.
• The synergistic blend of three esters gives improved lubricity, reducing friction and enhancing the oils performance.
• CFS 5w40 provides the optimum balance between hydrodynamic and boundary lubrication and the power absorbed through pumping losses to ensure maximum power release.
PERFORMANCE PROFILE:
• Ideal for fast road or track day use, especially in engines where a 5w30 is normally specified.
• Suitable for operating at 125°C with peak temperatures up to 150°C.