Today in the Signal Garage Auto Care auto care blog, we’re going to talk about oil change intervals. It seems that as engine technology advances, recommended oil change intervals have gotten longer for Signal Garage Auto Care customers. High quality oil in a well-engineered foreign cars engine has lead to extended intervals. But it’s also lead to some confusion among St. Paul auto owners.
The old mantra “change your oil every three months or three thousand miles, whichever comes first” once applied to every vehicle on St. Paul freeways. Time and miles take their toll on motor oil. But now, you could have a different oil change recommendation for every car or truck you own.
St. Paul car owners are like everybody else, they have a tendency to follow the oil change schedule of the vehicle with the longest interval. Of course, that can lead to problems. 
For example, recently four of the world’s largest auto manufacturers shortened the published intervals for several of their engine models. They originally published intervals that extended out to a much as 8,000 miles.
In real world St. Paul driving, the oil started to sludge up before the recommended change interval. Oil sludge is a thick jelly-like substance. Quite literally petroleum jelly – like Vaseline. This goop was clogging foreign cars small engine passages so the oil wouldn’t flow to some parts of the engine. This resulted in engine damage. We see it too often at Signal Garage Auto Care in St. Paul.
The manufacturers began to offer an extended warranty to cover sludge damage. But there was a catch: the vehicle owner had to follow a new, lower service interval, and provide proof of oil changes in order to make a warranty claim.
So here’s the bottom line: with longer oil change intervals, it’s essential to follow them closely. Back in the day of 3 months or 3,000 miles, if you went an extra month or an extra thousand miles, your oil was still fresh enough that it didn’t have time to build up much sludge.
But if your recommended interval is 6,500 miles and you go over another thousand, you’re getting into heavy sludge territory. You absolutely need to follow mileage intervals very closely. And don’t forget your severe service schedule. If you do a lot of stop and go driving in MN, short trips, drive in dusty or polluted St. Paul conditions, hot or cold weather, or haul heavy loads, you’re driving in severe service conditions. Your Signal Garage Auto Care advisor can help you determine which schedule to follow.
So check your foreign cars owner’s manual or talk with your Signal Garage Auto Care service advisor about where and how you drive in St. Paul. Should you change your oil closer to the regular schedule, or the severe service schedule? You need to make the call.
Let me give you an example of this. Some newer foreign carss have an oil change indicator. It has a sophisticated computer algorithm that tracks number of cold starts, engine temperature, RPMs, mileage, and many more variables to come up with a recommendation for when to change the oil.
Depending on driving conditions, the indicator in one test vehicle came on at anywhere from 2,500 miles to almost 7,000 miles. It’s typically just over 4,000 miles. Clearer sometimes, we’re driving easy miles that are easy on the foreign cars – like a long road trip. Sometimes, we’re driving hard MN miles – like towing a heavy trailer or a lot of around town driving. But, usually, it’s a combination of both.
Once again, it’s up to you to make the call as to when to change your oil at Signal Garage Auto Care to protect your foreign cars engine. Another place where MN car owners can go wrong is with the type of oil they use. More and more new cars are coming to St. Paul owners filled with synthetic oil. Without going into a lot of detail right now, let’s just say that synthetic oil lasts longer and is very resistant to oil sludge.
But it also costs quite a bit more, so some St. Paul people are tempted to use conventional oil for their oil changes. Now, it’s always best to use the oil recommended by your manufacturer. Check your owner’s manual see if a conventional oil alternative is allowed.
But getting back to the problem, if your foreign cars came from the factory with synthetic oil, the recommended oil change interval is for synthetic oil. If you use conventional oil, you can’t use the synthetic interval. You need to shorten it.