Synthetic vs. Conventional Oils

All name brand oils produced today are quality products compared to what was available years ago. Synthetic oils were borne out of our national defense program where vehicles needed to operate under extreme conditions with infrequent service. After all, Tanks & Humvees needed to start & run reliably in both the Arctic as well as in the Sahara. Hence synthetics were developed to offer better cold start & hot weather running protection relative to conventional motor oils. Synthetic oil service intervals could also be extended as the oils were more stable & resisted breaking down. Your BMW will run on either oil. The two oils are also able to be mixed if you need to top one off with the other in a pinch. 

At Schneller, we follow BMWs recommendations when choosing oils for your car. If  BMW insists on a synthetic oil,  then that’s what we‘ll use in your car. We’ll also recommend a synthetic oil if your car experiences extreme use,  for example racing or if your BMW is equipped with an exotic BMW Motorsport engine. While a single Synthetic Oil Service is significantly more expensive than a Conventional Oil Service, annual Oil Service costs will be about the same for the two (or only slightly more expensive for the synthetics) as synthetics with their extended service intervals will require fewer oil changes within a given 12 month period when compared to a car run on conventional motor oil.

The 15,000 Mile Oil Change

In our opinion, changing your oil every 2500-3000 mile is a WASTE of money & resources. The Quick Lube Industry however has done a great job marketing everyone into believing that it is necessary. They are after all, in the business of selling oil.

We recommend oil services based on a number of factors:

• Driving Style

• Synthetic vs. Conventional Oil

• Time of Year

• Visual Condition of Oil.

In addition to lubricating the moving parts within your engine, oil also serves to hold in suspension water, dirt & metal shavings that are too small for the filter to capture. Like a glass of milk, there’s a certain amount of “chocolate”  (in the case of engine oil, contaminants) that you can ad before a saturation point is reached & the “chocolate” or in the case of engine oil, contaminants, begin to settle out. These sediments form a thick tar like sludge that will clog oil passages & are generally not good for your engine. Water vapor accumulation (water is a byproduct of combustion) is also detrimental to the engine as water is a poor lubricant, promotes rust & will freeze up crank case ventilation systems in cold weather resulting in engine failures.

What do we think of the 15,000 mile oil service?  

We simply think the service interval is too long for a number of reasons.

First, if the car is only driven 5000 miles a year, that means  that no one will have examined the car in 3 years. That’s just too long for a complicated machine to travel without some looking after. Imagine not having a physical or going to the dentist for  3 years because your life has been somewhat inactive!

Secondly, long service intervals “suggest” that you only need to ad gas and drive. One customer drove his car for an entire year & at 15,000 miles finally came in for an oil service. The engine was ticking loudly and contained only one of the seven quarts of oil that the engine required. Where did all the oil go? As engines are run, they will consume (burn) some oil. Because of the extended oil service, he never even thought to check his oil level. Regardless of oil type & oil service interval, engines do consume oil & the level needs to be checked periodically.

Thirdly, long oil service intervals promote internal sludge & water build up. We’ve already replaced 2 engines that were on this extended oil service program. The first (a 2001 X5) had traveled only 22,000 miles when the crankcase breather system froze in cold weather causing catastrophic engine failure. The second (a 2000 330i) consumed much of its oil as the crankcase breather was clogged with sludge forcing the oil back into the intake where it was consumed by the engine. Ultimately the car ran out of oil and required an engine replacement. We’ve been able to avert disaster on 3 other engines. These customers now change their oil every 3 to 4 months.

So what does Schneller recommend as an appropriate oil service interval?  

Based on our experience, the following table provides some general guidelines:

Oil Type                                   Mileage                        Time                Average Annual Cost

Synthetic                                  7000            or              Every 4 months             $390

Conventional                            4500            or              Every 3 Months             $300
                                                                                                                                               

A consistent engine oil service schedule will keep engine oil clean and free of crankcase water build up. Moreover, it provides the opportunity for one of our Technicians to spot a potential problem elsewhere on your car before it happens. Additionally, seasonal oil services will allow us to match engine oil weights according to ambient temperatures thereby offering better engine protection & easier winter starts.

Visual Oil Inspection

Old muddy oil on the left…                                                           New clear oil on the right

If you’re not sure when to change your oil, remove your dip stick & run the tip across your finger. If you can still see your finger through the oil, then it’s not saturated with dirt & probably still OK.. If it looks muddy, it probably is, & needs to be changed. This visual method works well in warmer climates where engines warm up quicker and they’re able to burn off trapped water vapor. 

If you live in a colder climate, drive your car less than 10,000 miles a year, or if you only drive for short distances (less than 20 minutes after each start) then you’re in danger of water build up in your crankcase & should change your oil based on a time schedule rather than a mileage schedule. This is particularly important in the late fall & through the winter months when trapped water vapor can freeze inside your engine.