One of the problems with engine oil discussions is that people tend to grab onto one number and use it to decide whether an oil is good or bad. Most of the time that number is viscosity or zinc content.
That is where a lot of the confusion between Red Line High Performance Motor Oil and Red Line Race Oil comes from. The Race Oil has considerably more ZDDP, so it is easy to assume that it must be the better choice for any performance engine.
There is a lot more going on than that.
Both oils use PAO and ester base stocks, but once we get into the additive package, the two oils are built around different operating conditions. Zinc matters, but so do detergency, fuel dilution, oil temperature, viscosity and how long the oil is expected to stay in the engine.
Start With the Base Oil
Both High Performance and Race Oil use a combination of PAO and ester base stocks.
PAO provides good stability across a wide temperature range, a naturally high viscosity index and strong cold-temperature performance. Esters add lubricity and film strength, perform well at high temperatures and also help with additive solubility.
That base oil matters because viscosity isn't controlled entirely by additives. A good base stock can naturally maintain its viscosity across a wider temperature range without needing as much help from viscosity index improvers.
From there, the additive package determines a lot of what separates these two oils.
ZDDP: More Isn't Automatically Better
ZDDP is usually the first thing people bring up when talking about performance oil.
ZDDP stands for zinc dialkyldithiophosphate. It is an anti-wear additive containing zinc and phosphorus that becomes active under heat and pressure. It is especially useful in areas where there is a lot of contact loading between components.
Red Line High Performance oils are in roughly the 1,200-1,300 ppm ZDDP range.
Race Oil is considerably higher at roughly 2,200-2,300 ppm.
That is a big difference, but we can't look at those numbers and say Race Oil provides twice the protection.
Oil chemistry doesn't work that way.
ZDDP is one part of the additive package, and there is a point where adding more is no longer beneficial. Excessive levels can contribute to corrosion and acidity, which is why the formulation has to be balanced instead of simply chasing the highest possible zinc number.
For most performance street engines, 1,200-1,300 ppm is already a substantial ZDDP level.
The higher levels in Race Oil make more sense when we start talking about engines operating under competition conditions where the loads, temperatures and service intervals are different.
The Detergent Package May Be the Bigger Difference
This is probably the part of the comparison that gets overlooked the most.
High Performance Motor Oil uses more detergent than Race Oil.
A street-driven engine may have the same oil in it for thousands of miles. During that time it has to deal with cold starts, short trips, moisture, combustion byproducts and normal contamination. The detergent and dispersant package helps control deposits and keeps contaminants suspended until the oil is changed.
A race engine usually has a very different service life.
Race Oil uses less detergent and puts more of the formulation toward frictional properties, film strength and dealing with fuel dilution.
That doesn't mean Race Oil has no detergent. It means the balance is different.
If an engine is going to see a race weekend and then have its oil changed, there isn't the same need to build the formulation around thousands of miles of contamination control.
On the other hand, if the car is driven regularly on the street and only sees an autocross, drag strip or road course occasionally, that detergent package still has an important job to do.
This is why I don't like looking at Race Oil as simply a higher-level version of High Performance Oil. They are built around different service requirements.
Fuel Dilution Changes the Conversation
Fuel dilution is another reason Race Oil is formulated differently.
Fuel getting past the rings and into the crankcase reduces the viscosity of the oil. In a race engine, especially one running rich mixtures, large injectors, alcohol fuels or spending a lot of time under heavy load, fuel dilution can become a significant part of the oil-selection discussion.
Race Oil places more emphasis on maintaining film strength in those conditions.
That doesn't mean every engine that sees a track needs Race Oil. It means fuel dilution becomes one more part of the decision.
If we have a street car that runs clean, reaches operating temperature regularly and doesn't have a significant dilution problem, the oil has a different job than what we are asking from the lubricant in a dedicated race engine.
Understanding the Viscosity Lineups
The viscosity choices between the two lines also show how differently they are intended to be used.
The High Performance gasoline oils are available in the more familiar multigrades:
0W20
0W30
0W40
5W20
5W30
5W40
5W50
10W30
10W40
10W50
10W60
15W50
20W50
The Race Oil lineup is labeled differently:
5WT Drag Race Oil
10WT Drag Race Oil
20WT Race Oil
30WT Race Oil
40WT Race Oil
50WT Race Oil
60WT Drag Race Oil
70WT Nitro Drag Race Oil
The important thing here is that the Race Oil names should not automatically be treated like conventional straight-weight oils.
For example, 20WT falls into a 5W20 range, 30WT into a 10W30 range, 40WT into a 15W40 range and 50WT into a 15W50 range.
That matters because simply seeing "30WT" on the bottle can give somebody the wrong impression of how the oil is actually going to behave.
Don't Pick Viscosity Just Because the Engine Is Modified
Another mistake I see is automatically moving to a thicker oil because an engine makes more power or gets used on track.
Power alone doesn't determine the correct viscosity.
Bearing clearances matter. Oil temperature matters. RPM matters. Oil pressure matters. The way the engine is built matters.
A tightly built race engine operating at controlled temperatures may be designed around a very light oil. That is why race oils such as 5WT and 10WT exist.
Another engine may have larger clearances, higher oil temperatures or significant fuel dilution and need a heavier oil.
Neither one tells us what should go in a completely different engine.
For a car seeing track use, one of the most useful things we can know is actual oil temperature. Coolant temperature doesn't tell us what the oil is doing.
If we don't know the oil temperature, we're missing an important piece of the viscosity decision.
What About Diesel Oil in a Gasoline Engine?
Diesel oil comes up constantly in conversations about older engines and performance engines, usually because somebody sees the zinc level and assumes it is a good substitute for a gasoline performance oil.
Again, zinc is only one part of the formulation.
Diesel engines deal with a much larger soot load than gasoline engines. Diesel oils need detergent and dispersant chemistry designed to keep that soot suspended and control soot-related deposits, oil thickening and abrasive wear.
A gasoline engine doesn't have the same soot problem.
That doesn't mean a diesel oil can't be approved for use in a gasoline engine. Some are. It also doesn't mean there is anything inherently wrong with a dual-rated oil when the specifications and viscosity fit the application.
The issue is choosing a diesel oil specifically because it has a higher zinc number.
Part of the additive package in that oil is there to deal with a contamination problem that a gasoline engine doesn't produce to the same degree. That needs to be considered along with everything else the oil is being asked to do.
High Performance or Race Oil?
This is where the actual use of the vehicle becomes important.
Take a car that gets driven on the street, goes to autocross events, sees an occasional HPDE and maybe makes a few passes at the drag strip. That engine can still experience significant load and temperature, but the oil also has to survive cold starts, normal driving and thousands of street miles.
That is a very different situation from a dedicated race engine where the oil may be changed after every event or after a relatively small number of operating hours.
For the street/track car, the detergent package and service life still matter.
For the dedicated race engine, the higher ZDDP level, reduced detergent package, film strength and fuel-dilution resistance may become more important.
There is also a lot of room between those two examples.
That is why I would rather know how the engine is being used than simply know how much horsepower it makes.
I want to know the engine combination, bearing clearances if they are available, typical oil temperature, RPM range, fuel being used, how much street mileage the car sees and how often the oil is changed.
That information gives us a much better starting point.
Look at the Whole Oil
The main point is that oil should be looked at as a complete formulation.
ZDDP is important, but there is more to the additive package than zinc.
Detergents are important, but the correct amount depends on what contamination the oil has to control and how long it will stay in service.
Viscosity matters, but the number on the bottle has to be considered along with actual operating temperature and engine clearances.
Race Oil and High Performance Oil solve different problems. Understanding those differences makes it easier to choose the oil that matches the engine instead of simply choosing the product with the biggest number on the label.