1: How often should I change my oil?
Quite simply – it depends. This certainly isn’t the ideal answer, but it is the most honest one. Temperature plays a major role in the frequency of necessary oil change intervals. Every 20°F increase in oil temperature beyond 220°F shortens the life of the oil by 50%. This means cars that run very high oil temps will have much shorter oil life than cars that have moderate oil temperatures. Interestingly, the same also goes for low temps. It may be surprising, but low oil temperatures (below 180°F) can also shorten oil life. In fact, low 120°F oil temps pose greater risks to your engine than 260°F oil temperatures do. The reason is because low oil temps allow more moisture and fuel dilution to build up in your engine.
Street rods that see many miles of highway driving at moderate oil temperatures can expect to go up to 5,000 miles between oil changes.
Owners of street rods that only see short-trip driving should change their oil every 3,000 miles, or at least once a year. It is important to always change the oil in the fall before you put your street rod away for winter storage. You want to drain all the moisture, fuel dilution and used oil out of the engine before you stop driving for the season. Make sure the crankcase has been refilled with fresh oil, and then you are good to go when the weather warms up in the spring. The oil will not go bad just sitting in your crankcase over the winter.
2: Do I need break-in oil, and how long do you use break-in oil?
While every engine can benefit from break-in oil, it is a must for flat tappet camshaft engines. Even roller cam engines benefit from break-in oil because the piston rings still need to break in, and a better, faster ring break-in means more power and less fuel dilution in the motor oil.
Driven recommends changing the break-in oil after 30 minutes if you have a flat tappet engine. You will then need to refill with break-in oil for the next 500 miles. After both the initial break-in and 500 miles of driving, you can then use an oil made specifically for flat tappet engines.
For non-flat-tappet engines, we recommend running the break-in oil for 500 miles. After that time you can install whichever oil you prefer.
3: What viscosity oil should I run?
The “technical” answer is to use the lowest viscosity possible for the engine bearing clearances, oil temperature and horsepower output. Most people don’t know all of this information though, so the “practical” way to determine the correct viscosity is to do one of the following:
1—Run as low a viscosity as will yield 25 to 30 psi oil pressure at idle when the engine is warmed up. This is more oil pressure than the engine needs, but it is not excessive. Oil pressure is one of those areas where moderation rules. Too much or too little is not good. You need moderation in oil pressure to prevent engine damage.
2—Use one viscosity grade lower synthetic oil than you currently run if you utilize conventional oil. This gives you the same high-temp protection as your conventional oil, but you gain all the benefits of a synthetic. For example, a street rod running conventional 20W-50 motor oil can safely switch to a synthetic 10W-40 and actually improve the protection of the engine.
4: Do I need to do anything special for winter storage?
Using an oil with storage protection additives is recommended. Some motor oils have extra rust and corrosion inhibitor additives that make them better suited for wintertime. Also, it is important to change the oil before you put your street rod away for the winter. You don’t want to store the engine on used motor oil. Fresh oil with extra corrosion inhibitors provides excellent winter storage.
5: Do I need to use a “high Zinc” oil after break-in?
You do if you have a flat tappet cam or very high valve spring pressures on a roller cam. Flat tappet and aggressive roller cam engines require higher levels of ZDDP than modern, stock engines from the factory. As a result, these engines need a steady diet of high Zinc oils.
We know this is a lot of information with lots of variables to take into account to protect your vehicle’s engine. Fortunately, Driven Racing Oil is a one-stop shop for everything from break-in oils to high Zinc motor oils with extra rust and corrosion inhibitors. We can provide everything you need to keep your muscle car or street rod engine running in peak form.