Without various oils and lubricants, no vehicle will go very far. The engine needs motor oil to lubricate and cool the bearings, pistons, rings, cylinders and other moving parts.
The motor oil you use should meet the viscosity and service ratings recommended in your vehicle owner's manual. Most engines today are factory-filled with 5W-30 because 5W-30 improves cold starting, fuel economy and allows the oil to reach critical upper valvetrain components in overhead cam engines more quickly than heavier viscosity oils. Most vehicle manufacturers also approve 10W-30 for year-round driving. But heavier grades such as 20W-40, 20W-50, straight 30W, etc. are formulated for higher temperatures and loads, and are too thick for cold weather driving. Extremely thin oils such as 5W-20 and even 0W-20 are for very cold weather only. As for choosing a type of oil, there are three basic types: conventional, synthetic and synthetic blends.
Conventional mineral oils are refined from crude stock and treated with additives such as detergents, viscosity improvers, anti-wear agents and corrosion, oxidation and foam inhibitors to improve their performance.
Synthetics are man-made and engineered to provide the best possible lubrication under the widest range of operating conditions, including extreme temperatures both hot and cold. Synthetic oils can withstand conditions that cause ordinary oils to oxidize and break down. They provide superior high-temperature protection, easier cold-weather starting and reduced friction for better fuel economy.
But synthetics are expensive so synthetic blends are also available as a more affordable alternative. A blend obviously can't deliver the full benefits of a 100 percent pure synthetic, but it's certainly a step up from a conventional oil.
Motor oil is a high-volume product because it needs to be changed regularly. Heat, wear particles from the engine and combustion blowby contaminants all cause the oil to break down as the miles accumulate. OEM recommended oil change intervals vary from 3000 miles or three months up to 7,500 miles or 12 months depending on operating conditions.
Some new vehicles don't even have a recommended change interval at all and rely instead on an "oil monitor" system to signal when a change is needed.
These oil monitor systems don't actually test the oil. They monitor driving conditions (engine speed, idle time, temperature, etc.) that affect oil life. Under ideal operating conditions, the oil change light may not come on for up to 10,000 miles or more - but that's under ideal operating conditions only. Most vehicles operate under "severe service" conditions in regular city traffic. Severe service includes short-trip driving (seven miles or less, especially during cold weather), extended idling, towing a trailer or driving in dusty conditions.
Because of this, the most commonly recommended interval for changing the oil and filter is still every 3,000 miles or three months, which ever comes first. Such frequent oil changes may not always be necessary, but oil is a lot cheaper than a new engine.
Oil life also depends on the type of oil used. Some suppliers of synthetic oils claim their products can go up to 20,000 miles between changes. Others are more conservative and say to follow the OEM recommended change intervals - especially if the vehicle is still under warranty.
OIL AND CRANKCASE ADDITIVES
A wide variety of oil and crankcase additives are available that can be offered to customers who feel they might benefit from the use of such products. These include additives to reduce oil burning and increase oil viscosity to quiet noisy lifters, additives to reduce friction and wear, additives that reduce oil leakage and cleaners for removing sludge from the crankcase in neglected engines.
The proliferation of new electronic automatic transmissions in recent years has created a whole new generation of ATFs. What's important here is to make sure the ATF your customer buys meets the OEM specifications for the transmission in which it will be used. If in doubt, refer to the vehicle owner's manual.
GEAR OILS AND GREASE
For manual transmissions and differentials, a single 80 or 90 weight gear oil or a multi-viscosity gear oil may be required. But some manual transmissions, transaxles and power steering systems, Dexron II or III ATF may be the specified lubricant. Some vehicles that have limited-slip differentials require a special type of oil for the clutch packs. CV joints require their own type of grease, but U-joints can typically operate just fine with chassis grease or multi-purpose grease. Wheel bearings always require a high temperature grease.
Other special lubricants that may be required for certain jobs include: moly-based brake grease for lubricating calipers and shoe pads; silicone brake grease for lubricating caliper and wheel cylinder pistons and seals; white lithium grease for lubricating door hinges, cables and other sliding mechanisms; dielectric grease for lubricating and protecting spark plug boots and electrical connectors; and anti-seize for spark plugs, oxygen sensors and fasteners. Finally, don't forget penetrating oil for removing frozen fasteners and dry lubricants such as graphite for lubricating locks.