Liquid Intelligence No. 237
ZDDP Oil Additive
From$129
Choose size and buyRestores the ZDDP protection classic and vintage engines were designed for.
- ✓Restores original ZDDP specification
- ✓Essential for pre-1996 flat-tappet engines
- ✓Protects camshafts and vintage valvetrains
- ✓4% by volume at each oil change
ZDDP Oil Additive
“For veteran, vintage, classic and pre-1996 muscle car owners who want to prevent engine damage, this specially formulated ZDDP engine oil additive puts back the ZDDP older cars need to bring them back to their original specification. It really does do exactly what it says.”
✓ 100% satisfaction guarantee: you have everything to gain and nothing to lose.
Modern oils have had ZDDP (zinc dialkyl dithiophosphate) taken out, but engines built before 1996 rely on it. Liquid Intelligence 237 puts it back, re-establishing the ZDDP levels classic and vintage engines were designed for.
It contains very high concentrations of ZDDP, the primary extreme-pressure ingredient in quality motor oils for over 70 years. It reduces the tendency of parts to scuff or gall under heavy loads and in high-performance motoring, and changes the bearing surfaces to prevent metal-to-metal contact.
It's compatible with all conventional and synthetic automotive oils, so you can use the base oil of your choice. It's recommended for veteran, vintage and classic cars, any vehicle built before 1996, and high-performance non-production racing cars.
Why ZDDP was taken out of modern oils
Zinc dialkyl dithiophosphate, or ZDDP, puts small amounts of zinc and phosphorus into the exhaust gas. They coat the catalytic converter, shielding it from some of the gas it's meant to treat: the same coating effect that protected the valve gear in older engines. With every new car now needing a high-performance catalytic converter to meet emission standards, ZDDP has been taken out of modern petrol engine oils.
Modern engines don't need it, because they use roller lifters rather than flat tappets. Cars built before 1996 have flat tappets, which need high ratios of ZDDP in the oil to control wear.
Some diesel engine oils still contain ZDDP, but they're highly viscous with a lot of detergent, which suits diesels but not higher-revving petrol engines: in a petrol engine they can starve the bearings of oil at high revs. Racing oils are formulated for short-term high performance, which is quite different from what an everyday car needs. The simple answer for an older engine is to put the ZDDP back.
Some off-the-shelf additives contain ZDDP, but only a little per bottle. 237 contains very high concentrations of it.
Instructions/How to Use 237
Add 237 at 4% by volume (40ml for every litre of oil) at every oil change. That keeps enough zinc and phosphorus in the oil to go on protecting the engine, whatever base oil you choose.
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- ✓ Prices in Australian dollars and include GST
- ✓ Direct from the manufacturer: formulated and made in Minchinbury, NSW
- ✓ Free technical phone support before and after purchase
Free expert help
Questions about your vehicle, or how to get the best result? Call Peter, who formulated it.
Call 1800 441 163Or 02 8188 2060 · 7am–7pm, seven days
