Answered By The Experts: VP Racing Tackles Your Oil Questions

This month’s expert in our Ask The Experts series comes to us from VP Racing. Technical Director Freddie Turza comes from the Research and Development division of VP Racing, and he’s played an integral role in the brand’s recent expansion into the oil and performance-lubricant market. With a resume rich with high-end racing engine building experience, Turza isn’t just some dude sitting behind a desk.

Traditionally known for its racing fuels, VP Racing’s lineup of performance chemicals covers a wide swath of the market beyond fuel-related items. This includes coolants, gear oils, brake fluid, power steering fluid, and car care chemicals. VP Racing’s oil lineup is made up of several lines of engine oils, which includes the conventional VP Classic, which is made up of mineral base oils with an advanced additive package. Then there is the VP Hi-Performance line of synthetic-blend oils, which is designed for a wide range of street performance-based applications, and the Pro Grade full-synthetic racing oil lineup.

VP Racing also has a complete lineup of API and ILSAC-certified oils within its “Street Legal” line of oils. These range from synthetic blends to full-synthetic. There is even an Extreme Service oil, designed for high-mileage vehicles. All are designed to comply with new-car warranty requirements. Add to that the line of break-in oil, nitro racing oil, and heavy-duty diesel oils, and you see that VP Racing is far more than just race gas. So, with that said, let’s jump into answering your questions.

As a longtime fan of auto racing — primarily drag racing — I have been surprised to observe many drag racers using high viscosity oils (both mineral and synthetic) in their boosted engines. Several from the Discovery show, “Street Outlaws” are using viscosities of 50 and higher. Question: As other forms of racing are going to much, much lower oil-viscosities and tighter bearing-clearances to take advantage of the reduced friction and derived efficiencies, why haven’t these guys followed their lead? – David G.

VP: Boosted engines make extreme cylinder pressures which cause major distortion and deflection. The clearances on boosted engines are much bigger than a normal naturally aspirated engine. Block composition and design cause the engine builder to use large bearing clearances and the heavier viscosity oils provide protection and also have a cushioning effect.

Does VP racing produce engine oil compatible with alcohol fuels to combat against wash down? Any lubricants that can be used with Nitro 50 fuel? Daniel F.

VP: All of our performance lubes work well with methanol fuels. Get the tune-up and the ring seal right, and the contamination will be minimal.

How do I choose an oil for drag racing? 10w-30? 20-50? Straight weights? I’m running high compression and nitrous and not getting much heat in the oil during early runs of the day, but I’m seeing higher temps later. – Eric T.

VP: That depends a lot on how the engine is clearanced. Block material, cylinder pressures, etc. will also come into play when choosing the proper viscosity. I recommend trying to stay with a multi-grade oil, so you have good oil flow when the engine is cold.

There seems to be an effort to phase out conventional oil, by the manufacturers and/or retailers, would you agree? And if so, why do you think that is? I refuse to believe that everyone needs synthetic oil. – Courtney H.

VP: This is true, but it is more related to lower viscosity oils (0W grades require full-synthetic base oil to meet that viscosity requirement) and that is because of the increase in fuel economy they offer. Also, smaller, modern engines (also becoming more prevalent because of increased fuel economy) require these lower viscosity oils.

I’d like to hear about Group 4 “True Synthetic” oils. Not necessarily pure Group 4, but with suitable additives. The true synthetic Group 4 oils are hard to find and expensive. Is there any value in paying the price? – Scott W.

VP: Group IV synthetic base-oils are polyalphaolefins (PAO). They are chemically engineered synthesized base-oils. They offer outstanding protection amongst a broad temperature range and are great for use in extreme cold and high heat temperature applications. In addition, they have excellent stability and molecular uniformity, and the light ends [the almost-pure portion of distilled crude oil that sits at the top of the distillation tower] do not volatilize as quickly as other base oils. When blended with a select balance of quality additives, make it a strong performer.

I have always assumed that an oil’s viscosity requirement (in a gasoline four-stroke engine) is determined based on crankshaft main and rod bearing clearance; is that true? Is there a guide or table that could be used as a starting point to figure out what weight oil is needed, based on the bearing clearance used? Also, are there other factors to consider, like RPM, operating temp, type of racing, street or marine use? Do any other factors come into play? – Bill U.

VP: You are correct. The needed oil viscosity is determined based primarily on main and rod bearing clearances. Other considerations include engine operating temperature, RPM, load, oil film strength, environment, type of racing, and so on. There are charts online (or talk to your engine builder) to identify what weight oil should be used for certain bearing clearances.

I’d like to know what, if any, the key differences are between fully synthetic oils and mineral-based (with additives) oils for the same use and same viscosity. Also, are all oil additives created equal? Both for mineral and synthetic oils. – Angus B.

VP: Mineral base-oil can use Group I, II (plus), or III base stocks, or a combination thereof. They contain different sulfur, saturates, and viscosity index levels. Group I base stocks are the least refined and mix hydrocarbon chains with little uniformity. Generally, this is used in less demanding applications; but certain cuts offer tremendous cling ability as compared to synthetics.

Group II (plus) base stocks have good volatility, better oxidation stability, and wear prevention. They have fair low-temperature performance. Group III base stocks use a hydrogen process to clean up the crude oil. This base stock has a higher viscosity index than Group I or II (plus) and provides better oxidation stability and excellent uniformity.

What is lacking with mineral base oils can be “made up” with a select balance of additives to improve their performance in certain applications. It should be noted that many engine builders still prefer mineral-based racing oils due to the cling-ability aspect of some of the base oil cuts. The synthetic group IV base stock is polyalphaolefins (PAO) which offer a much broader performance temperature range than mineral oils.

The light ends do not volatilize as quickly as the light ends of mineral base oils. These stocks are great for use in extreme cold and hot engine conditions. In addition, they are strong performers when used in motor oil. They are more expensive than the mineral base oils but less expensive than Group V base oils.

Group V base stocks are chemically engineered oils. They are typically esters, polyglycols, and silicone. They offer many performance advantages over mineral base oils but are very expensive. Some motor oils use a combination of Group IV and V base oils due to the cost of Group V. Often these base stocks are used in industrial applications.

Finally, not all additives are the same. It is important for oil manufacturers to match up select additives to the performance of the base oils to provide maximum protection for racing and consumer engines.

The way I understand oil viscosity is the first number of the “10W-30” is the cold oil flow rate, and the second number is the hot flow rating. Taking this into consideration why isn’t a 5w-50 or a 0w-50 weight oil a “go-to” oil for all applications with the widest spread between the hot and cold rates? What would be the disadvantage of this? – Mike M.

VP: The SAE 0W-50/5W-50 motor oils are often used in select racing, high-performance, and exotic engines where low-temperature pumpability (start-up), fuel economy (in some cases), and excessive heat operating temperatures are a concern. In selecting a motor oil, you are looking for “optimum performance” for a particular engine.

With tight clearance engines, the 0W works well but the SAE 50 weight portion may be too viscous, causing increased fluid friction which leads to higher operating temperatures, loss of horsepower (frictional drag), and oil oxidation/degradation. In determining what viscosity of motor oil should be used in your engine, the common rule is to base your selection on the main- and rod-bearing clearances.

Other considerations include operating temperature, RPM, load, oil flow, environment, etc. It is important to follow the OEM and/or your engine builder’s oil recommendations based on set clearances and temperature ranges of the application.

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About the author

Greg Acosta

Greg has spent fifteen years and counting in automotive publishing, with most of his work having a very technical focus. Always interested in how things work, he enjoys sharing his passion for automotive technology with the reader.
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