Comma Classic and Vintage SAE 40 Motor Oil. Comma Oil Product Features Traditional, non-detergent motor oil for 4-stroke petrol engines. Specially designed for the needs of Classic & Vintage cars. Higher viscosity prevents oil from leaking. * Minimises engine noise. Monograde Oil for Summer. Ensures high temperature performance and best starting conditions in summer thicker oil can maintain oil film at high temperature. Oil change every 600 miles. Comma Oil Service Classification: SAE 40 API SA In 1965 Comma Oil was born and quickly became the major supplier to the Independent Vehicle Workshops and DIY motorists of the time. The motor oils that Comma produced then have, over the years, been updated to meet the demands of the newer technology engines leaving the Classic cars of the 60s, 70s and 80s without the motor oil for which they were designed. The Comma Classic Range re-introduces not only the original 20w50 Motor Oil for the period but also includes the SAE 30 and SAE 40 non-detergent monogrades formulated as they were in the past. Why do Classic cars need classic oils? Modern Oils (= fully & semi synthetic oils), especially lower viscosity grade oils are often too thin for engines in older cars. Oil additives in modern oils tend to dry up old gasket materials like leather, cork & felt – Resulting in Oil Leakage. Whilst modern engine oils do offer benefits in cold weather conditions, most classic & vintage cars are driven during spring/summer. Detergent Additives in modern oils can clean up old engines which can lead to lack of compression and other engine issues.