Salt air, water in the fuel, and long idling at the dock are hard on an engine that also has to run flat out. SFR's chemistry was built to stay on the metal when water gets in, and the fuel conditioner was tested for exactly the water and rust problems a marine tank has.
Every fortifier follows the same published dose — 1½ oz per quart (5%) the first time, 1 oz per quart (3%) at each change after — except where friction is part of how the unit works. Those rows are marked.
| System | Product | Dose | Why |
|---|---|---|---|
| Four-stroke gasoline inboards and outboards | GASZOL Gas Engine Oil Fortifier | 1½ oz per quart (5%) first application · 1 oz per quart (3%) at each change after | Extreme-pressure protection for the valve train; no sulfur or phosphorus, so it is safe with catalyst-equipped engines. |
| Marine diesel — inboards, gensets | D-SOL Diesel Engine Oil Fortifier | 1½ oz per quart (5%) first application · 1 oz per quart (3%) at each change after | Soot control and bearing protection for engines that idle for hours and then load up hard. |
| Lower units, gear cases, V-drives (gear oil) | GEARZOL Gear Oil Fortifier | 1½ oz per quart (5%) first application · 1 oz per quart (3%) at each change after | Extreme-pressure fortifiers for the pinion and corrosion protection when water gets into the gear case — which it does. |
| Marine transmissions running ATF or friction plates | Not recommended | Not recommended — friction is what makes it work | If the transmission needs friction to engage, leave it alone. Call if you are not sure what yours runs. |
| Two-stroke outboards (premix or oil injection) | Call 800-735-6438 | Call us | No fortifier: they are built for an oil sump. Use ProTecta Synthetic 2-Cycle Oil instead: synthetic, marine approved and very low smoke. Ask your distributor or call 800-735-6438. |
| Diesel fuel — summer | D-SOL Lubricity / Cetane | 1 gallon treats 400 gallons of diesel — every fill | Lubricity for the injection pump, cetane boost, injector detergency. |
| Diesel fuel — stored, seasonal, winter | D-SOL Multi-Function All Season | 1 gallon treats 400 gallons of diesel — every fill | Rust protection in the tank, stability in storage, water tolerance without forming an emulsion. |
| Steering, trim and tilt on hydraulic oil | H-ZOL Hydraulic Oil Fortifier | 1½ oz per quart (5%) first application · 1 oz per quart (3%) at each change after | Pump protection and cold-start flow for the hydraulic side of the boat. |
| Steering, trim and tilt filled with ATF | Not recommended | Not recommended — friction is what makes it work | Anything that calls for ATF gets no SFR fortifier. The one product for it is ProTecta Synthetic Transmission Treatment. |
| Winches, trailer bearings, exposed fittings | SFR 2522 Extreme Pressure Grease | Pack bearings two-thirds full | Fortified with moly and graphite; holds up in bearings exposed to water, steam and detergents. |
| Frozen fittings, rusted hardware | SFR Lubricant & Penetrating Oil | Soak, then work it | Wet or dry it repels and displaces water. Non-flammable solvent. |
Check what your manufacturer specifies for each unit. Many late-model transfer cases, and some manual transmissions and transaxles, call for automatic transmission fluid rather than gear oil. Rule of thumb: anything that calls for ATF (transmissions, transfer cases, trim and tilt units, power steering) gets no SFR fortifier, H-ZOL included. The one product for ATF is ProTecta Synthetic Transmission Treatment. A tractor whose hydraulics share one fluid with the transmission, wet brakes or PTO clutch gets 1% only. When in doubt, call 800-735-6438 before pouring.
Prices and treats-up-to are the shop's own figures. Quarts and gallons ship free over $100; pails ship boxed by FedEx Ground at a flat rate. Not sure how much you need? Use the calculator.
One gallon treats 400 gallons of diesel.
Numbers are the laboratory's, run at the leading independent labs in the U.S. — see Proof & Testing.
Yes — GEARZOL at the standard rate: 1½ oz per quart of gear oil the first time, 1 oz per quart at each change. It carries corrosion protection for the water that gets past the seals.
Don't add a fortifier; they are formulated for an oil sump, not for premix or oil injection. For two-strokes SFR carries ProTecta Synthetic 2-Cycle Oil: synthetic, marine approved and very low smoke, in quarts and gallons. Ask your distributor or call 800-735-6438.
D-SOL Multi-Function All Season. It protects the tank against rust, keeps stored diesel stable, adds lubricity for the injection pump, and tolerates water without forming an emulsion. One gallon treats 400 gallons.
GASZOL contains no sulfur or phosphorus, so it is safe with catalytic converters.

Made by SFR Corporation under our ProTecta consumer brand. Buy them at protectaoil.com or from your SFR distributor.


Pull an oil sample before you treat and another at the next drain, and compare the wear metals. Same independent lab, your machine, your numbers. Or call 800-735-6438 with your equipment list and we will spec and price it.