These are the methods California Datsun uses and considers to be proper break-in and startup of a general engine. Customer is required to follow these break-in methods in order to perform under the Limited Warranty.
Bearings generally don’t need break in. What we want to concentrate on is seating the rings against the cylinder walls to ensure high compression for the engine’s life. This needs to be done properly early on.
Immediately upon first startup, check the oil pressure and bring the engine up to 2,000, listening for noises, looking for leaks, adding water, etc. Try to use as little choke as possible as the extra gas can wash the oil from the cylinder walls and can affect ring seating. Don’t race the engine, but blipping the throttle is fine. Let the motor idle at 2,000 until it reaches full operating temperature. Once at full temperature, bring it down to idle, recheck the timing, sync the carbs.
If all seems solid, go for a test drive as soon as possible. You need a road with little traffic or a parking lot for this next step. Once on the road, accelerate moderately up to 3,500 or so in a lower gear. Let off the gas abruptly. Let the engine braking pull the motor 1,500 or so. Do this 10 or more times in the lower gears in different rev ranges. This is a well-known method which uses the engine vacuum to pull the rings against the cylinder walls to ensure proper seating.
After these initial “throttle dumps,” do some moderate driving at different speeds around the area. Continue to do moderate acceleration, occasionally backing off the throttle as before, using the engine vacuum to brake the motor. Some people say the rings seat immediately, but I like to take my time over the first couple hundred miles to let the rings seat smoothly.
By the time you get a couple hundred miles on the motor, you will notice the idle is smoother and more stable with smoother revving and an all-around better feel. If your cylinders have been bored properly or are finely honed, ring seating is generally quick at a couple hundred miles. If your cylinders are roughly honed, it might take you up to 1,000 miles. Doing a compression check will tell you for sure.
Don’t start doing zero-to-60 runs with the startup oil in the crankcase as it has pre-lube remnants and other contaminants in it. Wait until after the first oil change, and at 500 miles, if everything seems stable and tight, start taking the engine to redline. Use your judgment from here on.
***YOU WILL NEED TO CHECK VALVE ADJUSTMENT AFTER BREAK-IN, .010 INTAKE AND .012 EXHAUST***
Fill the oil filter and the oil pump with oil prior to startup to create instant oil pressure. You can’t prime the engine with a drill the same as a V8, but you can crank the motor for 15 or so seconds with no plugs in to distribute oil and raise the pressure. Cranking it over with no plugs removes any load from the engine bearings which is very desirable. It’s also a good idea to pour some oil over the cam, valve train, and front chain. Worried about cam break-in? Just turn the motor over several times without plugs before you reinstall the rocker arms.
Oil Weights and Brands
Despite what your old manual says, don’t use 10W-40. It was common in 1974, but no new car engine today uses it. Instead, use 10W-30. Because it’s thinner, it will free up a couple of horsepower, rev faster, and will reach all bearing surfaces more quickly. We consider Castrol 30W the best single-weight, Castrol 10W-30 the best multi, and Mobil1 10W-30 the best synthetic. For a higher ZDDP level oil, Valvoline VR1 racing oil is the oil of choice in L-series engines.
The quality of the oils used today versus what was available in the 1970s is night and day. Back then they sludged up motors and filled oil pans with glop. Today’s SM API-rated oils have much more detergent and anti-varnishing abilities and are said to be stable out to 10,000 miles. It’s amazing so many Z engines made it to 200,000 miles using that oil. It really says something about the quality of the engines as a whole. HOWEVER…older engines with mechanical valve tappets like the L-series and V8s with flat tappets (not roller cams) were designed for motor oil which contain a moderate amount of zinc and phosphorus known as ZDDP (zinc dialkyldithiophosphate). ZDDP is considered a miracle lubricant for engines and has been used for about 60 years in motor oil and greases worldwide.
While zinc is not directly harmful to the environment, if it is burned due to ring blowby, it ruins your catalytic converter. So over the last decade, the EPA has pressured the oil companies to reduce the percentage of ZDDP in their passenger car oils. This extends the life of converters which, in turn, reduces total car emissions. SM-grade oils all have about .08% ZDDP to conform to EPA standards, while 2% and higher ZDDP is considered the level to shoot for.
Pressure from the construction industry allows some diesel oils like Rotella T, made by Shell, to use higher levels of ZDDP, which they claim is needed on heavy equipment. However, we don’t like the idea of using bulldozer-grade oil in a 7,000 rpm L28, even if it does have zinc. Starting in 2007, construction equipment has tighter emissions standards, so zinc in Rotella is likely to diminish eventually.
Luckily, there is still one company with the gust to market a higher ZDDP oil for passenger cars in a viscosity that doesn’t reduce horsepower: Valvoline. Their VR1 10W-30 racing oil is a quality SH-grade oil, which simply means the ZDDP hasn’t been removed to qualify as an SL or SM grade. Valvoline’s MSDS sheet lists it as 1.3% phosphorus/zinc, 1% sulfated ash, and 2.5% calcium, which makes for a nice lube cocktail. Valvoline states it exceeds SM levels of protection, so this is now our oil of choice. The best place to find it is at NAPA stores. It also comes in a 20W-50 version, but that may be too thick for an L28 motor.
Oil filters don’t increase horsepower or make the engine breathe better; they filter the oil. The particle size considered to cause the most wear is said to be around 10-30 microns in diameter. What you need is a filter which can reliably filter the smallest particle size from your oil supply. Be careful using racing oil filters as many are designed for maximum flow by allowing everything up to 50 microns or so to pass into the engine, which is fine if you tend to rebuild your motor every season.
Consumer Reports named FRAM the best on the market, and I have used them since 1980 without any problems. However, FRAM is starting to include “additive gel” in some filters to “infuse into the oil,” which worries me that they’re going down the Slick 50 path. WIX filters appear to be of high quality and filters down to 19 microns. Their advertising is aimed at people who understand engines, instead of the Slick 50 crowd. The filter they list for 1970-83 Z car engines is #51521.
NAPA makes a high-quality filter with Part #1521, which filters down to 19 microns and is easy to find. Interestingly, the specs between WIX and NAPA are identical, and it appears that they may be the same filter. Between the identically spec’d pair, I use the NAPA because it’s easy to find and the black case looks great against a blue block (WIX is plain white). The NAPA name may conjure up thoughts of truck parts, but isn’t that what you want…a quality filter designed for long service duty?
DON’T use the black metric bolts available in many parts bins. Use stainless steel for everything, or zinc. While black bolts look great when new, the black oxide they are covered with is not rust-resistant and rusts heavily within a few days from exposure to the elements. (I’m not sure why anyone would make a machine bolt that is not rust-resistant; seems like a useless product.) Also, I would try not to reuse the old bolts unless originality is a concern. Reinstalling rusty, 40-year-old bolts is romantic, I guess, but is just like using old seals; false economy.
Metric or Standard
Don’t insult this car by tapping out a bolt hold and installing SAE bolts. It has enough trouble keeping the Japanese styling and look without all its metric bones being replaced. TIP: While SAE bolts come in a simple “fine” and “coarse,” metric 10mm bolts come in 1.00, 1.25, 1.50, and 1.74 thread pitches.
Anti-seize is a brush-on silvery paste made out of molybdenum disulfide. When used on threads, it keeps bolts from seizing, literally, forever even in wet or high temperatures. Done in conjunction with tapping the holes ensures yourself, and any future owner, a car with easily loosened but properly tightened bolts. Get it at better parts stores. Very recommended. When possible, use anti-seize on EVERY bolt on the car before replacing them.