The Other Additives section gathers the engine, oil, cooling-system and transmission additives that don't fall under the dedicated Fuel Additives category but that solve specific service issues on a classic car. The products range from oil stabilisers that thicken a tired engine's oil pressure during a final season before rebuild, through cooling-system flush products that strip decades of accumulated scale and corrosion from a brass-cored radiator, to the gearbox and axle additives that improve synchromesh action on an A-Series or B-Series box that is starting to feel its age.
Oil Stabilisers and Engine Additives
Oil stabilisers, thicker, higher-viscosity additives that raise the operating viscosity of the engine oil without changing its cold-start behaviour, are useful on engines where wear has opened up bearing clearances and the standard 20W/50 multigrade is no longer maintaining hydrodynamic film pressure at hot idle. A dose of stabiliser raises the hot viscosity, restores oil pressure on the gauge, and buys the owner time to plan a full engine rebuild. The product is not a long-term solution, the right answer to an engine showing low hot oil pressure is to renew the bearings, but it is a useful workshop tool. Engine flushing additives, run through the sump and drained with the next oil change, lift accumulated sludge and varnish from the inside of an engine that has been on the same low-detergent oil for many years.
They are particularly useful as part of a recommissioning service on a car that has been laid up for a long period.
Cooling System Treatments
Cooling-system flushes are formulated to strip accumulated scale, rust and corrosion deposits from the inside of a classic cooling system, particularly useful on brass-cored radiators that have been running on poor-quality water without proper antifreeze for decades. The flush is run for a short period, drained with the old coolant, and the system refilled with clean water and the appropriate Forlife or standard ethylene-glycol coolant. Cooling-system corrosion inhibitors are stocked for owners running a system on plain water during summer touring, adding the inhibitor protects the brass, copper, gunmetal and cast-iron components from corrosion without the antifreeze concentration needed for winter use.
Gearbox and Axle Additives
Gearbox additives, including the friction modifiers stocked for owners running cars with worn synchromesh on first or second gear, can extend the usable life of a tired gearbox by a season or two, easing the shift quality and reducing the crunch into gear. They are not a substitute for a synchromesh rebuild but they can be a useful workshop tool on cars where a full gearbox rebuild is planned for the next winter. The corresponding axle additives are stocked for owners with a noisy or whining differential, again, not a long-term repair but a useful interim measure on cars where a full diff rebuild is planned for a future date.