Classic car oil: choosing the right oil for an older engine

Use the oil the engine was designed for, which the car's handbook or workshop manual gives. For many classic cars that is a mineral multigrade such as 20W-50, and for some older engines a single-grade oil such as SAE 30 or SAE 40. Modern low-viscosity oils are made for modern engines and are not usually the right choice for a classic.

Why do classic cars need different oil?

Older engines were built to looser tolerances than today's, and many were designed around thicker oils. Modern oils are also made for engines with catalytic converters and particulate filters, so the amount of some anti-wear additives they can contain is limited. An engine built for a different kind of oil is better served by one made for older engines.

Should I use 20W-50 in my classic car?

If the handbook gives it, yes. 20W-50 is the grade a great many British classics were built for. Some later classics list a thinner multigrade, such as 10W-40, so always check the manual first.

What is a single-grade oil, and when do I need one?

A single-grade, or monograde, oil such as SAE 30 or SAE 40 has one viscosity rating and no winter rating. Some vintage engines, mostly from before multigrade oils became common, were designed for one, and their manuals say so. If yours gives a single grade, use it. If it gives a multigrade, stay with a multigrade.

Can I use modern synthetic oil in a classic car?

It is not usually the best choice. Most classic engines were designed for mineral oil and run best on it, in the grade their manual gives. If an engine has been rebuilt with modern parts, follow the advice of whoever rebuilt it.

What about a classic Mini?

The original Mini puts its gearbox in the engine's sump, so one oil lubricates both. When the Mini arrived in 1959, it was Duckhams Q20W-50 that solved the problem, one of the moments in our history. If your car shares its engine and gearbox oil, follow its manual on which oil to use.

Which Duckhams oils are made for classic cars?

• Classic Q 20W-50: a mineral multigrade for older engines and hard-working conditions.
• Classic Q 10W-40: a mineral multigrade for classic cars whose manual gives a 10W-40.
• Classic Q SAE 30 and Classic Q SAE 40: single-grade oils for vintage engines that need one.

Duckhams introduced Europe's first multigrade motor oil, Duckhams Q, in 1951. See the whole Classic Q range.

What should I do before laying a classic up for winter?

Change the oil before you put the car away, so old oil, and the moisture and acids it has picked up, doesn't sit in the engine for months. Check the level before you start it again.

Questions

What oil should I use in a classic car?

The grade its handbook or workshop manual gives, usually a mineral oil. For many British classics that is 20W-50.

Can I use 10W-40 instead of 20W-50 in a classic?

Only if the manual lists 10W-40. Use the grade the engine was designed for.

Where can I buy classic car oil?

See Where to Buy for stores and online shops that sell Duckhams.