In the automotive world, there are some topics or questions that, if not quite taboo, are just asking for trouble. Like politics or religion, it’s generally not wise to ask a Corvette diehard about his or her favorite Mustang, say to a Mazda Miata lover their sports car is overrated, or troll a Toyota Land Cruiser owner by telling them a Jeep Wrangler is more reliable.Similarly, asking car enthusiasts about their favorite engine oils can lead to hours of heated debate. I have some thoughts about oil, particularly synthetic lubricant, which I put in practically everything, almost. The Ultimate Defense Against Wear And Friction Bring a Trailer Oil has come a long way since this slippery hydrocarbon was first extracted from the ground and used as a lubricant. Modern oils – even conventional, old dinosaur juice – do a fantastic job protecting engines from corrosion, wear, and damage. Oil also helps keep internal components cool, while detergents help prevent deposits and other buildup from forming over time. Finally, modern engine oils contain a broad spectrum of additives that reduce friction and keep seals, gaskets, and rubber components pliable to prevent troublesome leaks. I Use Synthetic In Nearly Everything Castrol Today’s conventional oils are certainly good, great, even, but synthetics take things to the next level. Without getting lost in the technical weeds, conventional oil is a highly refined version of what gets pumped out of the ground, while synthetic lubricant is cooked up in a laboratory.A purer product, synthetic does a better job protecting against wear. Benefits include, but are not limited to: Flows more easily at frigid temperatures Holds up to high heat far better Lasts much longer than conventional oils Can even help improve engine output and efficiency (if only slightly) For these reasons, and more, I’ve exclusively used synthetic oil in nearly all my cars as well as lawnmowers, tractors, generators, and other machinery powered by four-cycle engines. It’s Never Let Me Down Craig Cole | TopSpeed Years ago, I owned a 2002 Ford Focus ZX3, which I put nearly 200,000 miles on (I even found some photos stashed away on my computer). A fun-yet-versatile little car with a five-speed manual transmission, I installed a performance cylinder head and camshafts to get a little more oomph out of the 2.0-liter Zetec engine. Output was still modest, but these upgrades – and a few others – really woke the car up.A stout and reliable little four-cylinder, that powerplant proved to be nearly bulletproof; I had no major engine issues while I owned the car, except for one. Eventually, a valve seat in the head receded slightly, eliminating the required clearance between the camshaft and tappet. This meant the valve never fully closed, dramatically reducing compression on one of the cylinders, leading to severe drivability issues. Opening Up The Engine Shows The True Benefits Of Synthetic Craig Cole | TopSpeed To correct this problem, I had to pull the head, not a fun job, but still plenty doable on this simple car. With everything apart, I got a good look inside the engine’s top end and at the cylinders themselves. After more than 100,000 miles since the performance head was installed, everything was spotless, absolutely pristine. There was not a spec of sludge to be found anywhere, the camshaft lobes and solid lifters showed zero wear, the aluminum of the cylinder head itself was still frosty white, even in crevasses where oil always sits, and the factory cross-hatching on the cylinders was still plainly visible, plus there was zero discernable ridge at the top of the cylinder bores.Resisting wear and preventing deposits, I always ran Mobil 1 synthetic in my Focus along with a factory Motorcraft filter. In my experience, this is a fantastic oil that’s reasonably affordable and available on store shelves just about everywhere, though some synthetics are even better. You pay for the privilege, but lubricants from Amsoil, Redline, Royal Purple, and others promise even greater longevity and protection. Regardless, I changed the oil in my Focus religiously every 10,000 miles, a simple and easy-to-remember service interval that kept the car running like new the entire time I owned it. The Same Goes For Other Engine-Powered Machinery Craig Cole | TopSpeed Similarly, I’ve never had a single engine issue with any of the equipment I’ve used synthetic oil in. Everything from the lawn tractor to the power washer to the backup generator has run flawlessly, something I attribute to good maintenance practices and quality oil. High-Tech Engines Deserve A High-Tech Oil Craig Cole | TopSpeedModern cars and trucks are marvels of engineering. They’re safer, more comfortable, and deliver better performance while being far more efficient than vehicles from just a couple of decades ago. Delivering this, so many modern cars are motivated by downsized, turbocharged engines with direct fuel injection.These diminutive but hard-working powerplants tend to put a lot of stress on the lubricating oil. They can run hotter than larger engines, plus they often have smaller crankcases that hold less, meaning the oil can reach the end of its useful life much sooner. Additionally, turbo and supercharger boost pressure creates much more blowby past the cylinder rings, which leads to more contaminants getting into the oil.In applications like this, I highly, highly, HIGHLY recommend running a top-quality synthetic oil and changing it far more regularly than the manufacturer recommends. Frequent oil changes are just about the cheapest insurance against expensive repairs. Some High-Performance Cars Get Synthetic Right From The Factory Cadillac Naturally, certain high-performance and luxury vehicles come filled with synthetic oil right from the factory. This ensures these complicated and powerful vehicles deliver the performance their drivers expect with the durability engineers (and, let’s be honest, accountants looking to keep warranty costs down) demand. According to Mobil, more than 70 different vehicles are filled with Mobil 1 synthetic oil at the factory, everything from Bentleys and Porsches to models from Cadillac, Mercedes-Benz, and even Nissan. There Are Some Arguments Against Synthetic Oil Buick Of course, as with many things in life, there are some arguments against using synthetic oil, though I feel these are all rather weak. Some drivers, for instance, may worry about compatibility issues between synthetic and conventional oils, but I’m not aware of this being a problem, like, at all. Further dispelling this argument, oil manufacturers also sell synthetic-blend oils, though I never buy these because you don’t know how much synthetic is actually in there. I’d rather just pay a little more for full synthetic and have a better idea of what kind of product I’m getting. It’s Often More Expensive Craig Cole | TopSpeed As alluded to earlier, another disadvantage of synthetic oil is that it typically costs more than conventional lubricants. As a higher-tech product that offers a wider range of benefits, this should be no surprise. Now, the good news is, oil and filters are quite regularly on sale at major auto parts stores, often bundled together as a package deal. If you don’t mind getting some dirt under your nails, this can make doing your own vehicle maintenance more affordable than you might think. Can It Lead To Leaks In Older Vehicles? StockSnap via Pixabay Another potential downside to synthetics is that they can reportedly cause leaks in older vehicles. The reason I’ve heard for this is that the molecules are smaller and more consistently sized, so they’re more likely to seep out of tired, old gaskets and seals. Again, in my somewhat limited experience at least, I have not seen this happen. Years ago, I helped a friend switch his old beater over to synthetic oil, and leaks were never a problem. Could this be a real issue? Sure, but I personally haven’t seen it. Sometimes, Dinosaur Juice Is Just Fine Craig Cole | TopSpeed Speaking of hoopties, there are some instances where I think synthetic oil is completely unnecessary. If you drive an old, beat-up vehicle that you don’t plan on keeping very long, just run the cheapest oil you can find. Similarly, if you’re leasing a car or truck that will be returned in a couple of years, why spend more on synthetic oil if you don’t have to? If dinosaur juice meets the manufacturer’s requirements, just use that.And finally, the only vehicle I don’t run synthetic oil in is my 1936 Ford V8 sedan, a car I fully restored from the ground up. Wait, what? Yes, you read that correctly. I do not use synthetic oil in my precious classic, and here’s why. Keeping It Old-School Is The Optimal Choice With This Classic Craig Cole | TopSpeed Most vintage car owners baby their rides. No expense is too high to keep them running their best. And synthetic makes perfect sense in high-powered muscle cars with radical camshaft profiles and heavy-duty valve springs. It makes sense to use synthetic oil in ultra-rare vintage vehicles or other exotics, too, but not necessarily in a Ford flathead V8.My ’36 probably only makes 100 horsepower – it’s hardly a performance car – also, I usually only drive this machine around 1,000 miles per year, equating to one annual oil change. And finally, even the cheapest conventional oil available today is orders of magnitude better than any lubricant from the 1930s. Simply put, though rather paradoxically, synthetic oil is huge overkill in a car like this. Overall, I run synthetic in just about everything because it keeps my vehicles and equipment running like new, but I would also argue that not everything needs this high-tech oil.