The topic of what engine oil to use is a loaded subject of truthfully unnecessary confusion. We’re going to talk about some engine oil basics and principles you can operate by when you need to add oil or if you are intending to take on your own oil changes.
Let’s start with the basics:
There are 3 primary types of oil – conventional, synthetic blend, and full synthetic. Conventional Oil is thicker and breaks down easier. Synthetic oil is thinner and is scientifically engineered to withstand harsher conditions for longer periods of time. Synthetic blend is just that – a blend of conventional and synthetic. The idea here was to save cost while gaining some of the benefits of synthetic oil.
Next is Viscosity, or Weight. This ranges significantly from 0W all the way to 140w for gear oil. Most all engine oils are in the 0W-40W range with a complicated exact specification in between dependent upon manufacturer. The lower the weight – the thinner the oil, the higher the weight, the thicker the oil.
What’s Causing All The Confusion?
The dilemma for you, the vehicle owner is the confusion of what oil to use should you need to add a quart or the best oil to use if you intend to do your own oil changes. The confusion comes from two primary forces:
1. Constantly evolving Manufacturer specifications
A few examples: Ford uses primarily synthetic blend but was not always that way – specification changed over time and was retroactive. Exact weight depends on engine which can have 4 or 8 different possible engines in the same car. BMW has almost always used 5W-30 full synthetic but in the last few years switched to 0W-30 Full synthetic and “specified” that as a backwards compatible option as well. Oh, and M cars require different oils all together….for the most part!
2. Keyboard mechanics
Go to any internet forum on cars and research a thread on what oil to use and watch the floodgates open; all sorts of self professed experts & professionals to people who have been using “x” oil for years and know better than the experts are adamant and divided about what the best oil is. Add in all kinds of marketing and branding on these performance oils “premium”, “performance”, “racing” and they sure sound better! The important thing to remember is none of these people are professionals and often don’t know any more or less than you do. Stick to the facts and don’t give another person’s opinion more weight than your own common sense.
Here are some guiding principles that you can operate out of to take the confusion out of Engine Oil:
*All vehicles say what oil is required in the Owner’s manual and often on a sticker on the engine or hood*
1. In an emergency to add a quart of oil, type & viscosity could honestly matter less in the grand scheme of things: what’s more important is to NOT run your car low on oil, ever. If your car calls for 5W-30 full synthetic and the gas station for the next 100 miles has 10w-40 conventional, your engine will work just fine on the “incorrect” oil to get by until you can get to your mechanic or next oil change. If you want to play it safe, 5W-40 full synthetic would be the best shot in the dark if you are unaware of your vehicle’s specification, it will not hurt any engines that specifies anything less.
2. In general:
- European vehicles take full synthetic. 5W-40 is a safe bet for VW, Audi, and Mercedes with 5W-30 specification for BMWs
- Domestic & Asian imports year 2000 and newer typically take synthetic blends somewhere in between the 0W-30 range and within the last few years are switching to full synthetics in several cases
- Diesel Engines require different specific diesel oil in most cases
- AMG, BMW M, Audi S and other performance vehicles often require specific oils. However, a regular synthetic will not hurt if you need to add a quart
3. Oil Brands are like Pepsi & Coke – no one is better as long as it is name brand, not store brand – Mobil 1, Castrol, Shell, or Valvoline. These guys all make the oil for the big car companies. For example, Castrol used to make BMW’s oil for over 20 years, now Shell does. Performance oil like Royal Purple or Lucas oil won’t hurt but there are no realistic benefits for the price tag on a street vehicle.
We hope you’ve learned something new in this month’s BMW technology post and as always,
If you do believe you are experiencing a malfunction with your vehicle’s performance, please contact us at 8335 W Sherman St Suite #200 Tolleson AZ 85353 or call us.