Tag Archive for: 20w-50

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Should A Thicker SAE 60 Oil Be Used To Fight Heat In Harley Engines?

AMSOIL V-Twin Synthetic 20W-50A reader asks: I’ve got a 2014 Harley-Davidson Road King. Is it OK to run SAE 60 oil in the engine rather than 20W-50? I’m thinking that a thicker oil would be better in on really hot days. I also hear that a thicker oil will quiet down engine noise.

Our answer: You are far better off using 20W-50. There is no upside to using SAE 60 in your engine.

A thicker oil like SAE 60 will actually retain more heat. The result will likely be higher operating temperatures with SAE 60, rather than lower. SAE 60 is fine for older Harley engines like the Knucklehead, Panhead and Shovelhead.

As for noise suppression, the thicker SAE 60 may suppress rattles or knocks. But that doesn’t mean that it is providing superior engine protection.

All-in-all, there is no mechanical upside to switching to a thicker oil.

The Upside Of Running 20W-50

An ultra-premium synthetic like AMSOIL V-Twin 20W-50 will deliver lower operating temperatures over conventional oils. Better yet, it is designed to maintain its viscosity when exposed to long periods of extreme heat.

AMSOIL’s testing has shown that V-Twin 20W-50 can withstand operation at 500°F while maintaining its original viscosity. See the AMSOIL V-Twin Torture Test. It will easily withstand long hours and heavy heat. So, if the concern is oil shearing, using a 20W-50 is not an issue.

Another upside to going with 20W-50 is lower friction. A good synthetic like AMSOIL will optimize throttle response and fuel economy.

What About Thicker Oil In The Transmission And Primary?

The same principles apply. Thicker oil will retain heat and is liable to cause stiffer shifting. Noise may be somewhat suppressed, but that doesn’t meant that wear protection is enhanced.

One is wise to use products that are designed for primary and transmission use. AMSOIL V-Twin 20W-50 is formulated for use in the transmission and primary chaincase. AMSOIL also offers dedicated primary and transmission fluids for Harley V-Twins. There is no downside to using the V-Twin 20W-50 is all three components. Either the dedicated fluids or the V-Twin 20W-50 will work extremely well.

Conclusion: It is always wise to use the viscosity suggested for your application. Your engine was engineered for 20W-50 and there is no the upside to going with thicker oil. SAE 60 may actually provide the opposite of what you are hoping for.

See all of our articles about Harley-Davidson Motorcycles And Oil

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Should I Use 20W-50 Or 10W-30 In Vintage Engine?

Chevy Big Block 427 L72 Spec Engine

Should this Chevy Big Block 427 get 10W-30 or 20W-50 motor oil? (photo credit: superchevy.com)

Updated- March, 2024

A reader asks: My street rod has a 1967-vintage Chevy big block 427 (L72 spec) with solid lifter cams. This car runs only in the summer and has an estimated 450 horsepower. I would like to run AMSOIL Z-ROD in this engine, but I’m really torn between 10W-30 and 20W-50. There’s so much debate on the internet about which grade to use. Can you offer any thoughts?

Answer: This is a very contentious and well-worn subject and there may not be a wrong answer. Generally, we would defer to the viscosity suggestion of the engine builder. But if there is no engine builder or they are not known, either 10W-30 or 20W-50 could be viable options. Note that Z-ROD Series now offers a 10W-40 option.

However, as your engine does put out significant horsepower, we would lean toward using 10W-40 or 20W-50.

If your engine sees very light duty or is built exceptionally tight, 10W-30 would be fine. If you are taking this car to the strip, 10W-40 or 20W-50 would be better choices.

About AMSOIL Z-ROD Synthetic Engine Oil

Regardless of which viscosity is chosen, AMSOIL Z-ROD products are formulated expressly for older engines. Packed with 1440 ppm of zinc and 1320 ppm of phosphorous (serious anti-wear additives), Z-ROD is a superior choice for classic engines. These anti-wear agents make Z-ROD Oils especially suitable for engines with flat tappet camshafts. Z-ROD is also ideal for roller cam engines.

Motor oils specified for modern cars and trucks have zinc and phosphorus levels in the 800 ppm range. Today’s cars and trucks have emissions equipment that do not react well to high zinc and phosphorus levels. Therefore the latest motor oil specifications require different chemistry to control wear.

But as emissions equipment are a non-issue for classic engines, this AMSOIL Z-ROD motor oil has no formulation constraints. The 100% synthetic base oil of Z-ROD provides tremendous shear strength and maintains consistent viscosity, regardless of high engine temperatures or hard operation.

There is absolutely no downside to going with a synthetic oil like Z-ROD in vintage engines. You will not see increased oil consumption or leaks. Z-ROD Oils also contain special additives that condition seals to extend their life.

As vintage cars tend to retire for the winter, AMSOIL also gave Z-ROD a healthy dose of anti-rust and corrosion agents. So you can rest well knowing your baby is well-protected whether she’s running or not.

So regardless of whether you opt for 10W-30, 10W-40 or 20W-50, you will have done your engine a favor by choosing the AMSOIL Z-ROD Motor Oil series.

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Should I Use 20W-50 or Gear Lube in My Harley Transmission?

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Update- May, 2024– AMSOIL now offers a dedicated V-Twin Synthetic Transmission Oil. This product is identical in performance and protection to the AMSOIL V-Twin 20W-50. The V-Twin 20W-50 and the dedicated V-Twin Transmission Fluid offer identical transmission performance and protection.  AMSOIL no longer lists the Severe Gear products as secondary transmission fluid options as suggested in this article. 

Which choice is better for Harley-Davidson transmissions?

AMSOIL V-Twin Synthetic 20W-50 Motorcycle Oil A particularly nice feature about AMSOIL 20W-50 Synthetic Motorcycle Oil is that it can be used in the engine, transmission and primary chaincase of Harley-Davidson motorcycles. But some riders wonder if a gear lube like AMSOIL Severe Gear Synthetic 75W-110 or 75W-140 is a better choice. Let’s explore this question.

For Evolution 1340, Twin Cam and Milwaukee-8 engines, AMSOIL’s first recommendation for the engine, transmission and primary chaincase is AMSOIL 20W-50 Motorcycle Oil. For the transmission of these models, they offer a secondary recommendation of AMSOIL Severe Gear 75W-110 and a third option being Severe Gear 75W-140. Some riders claim to experience quieter operation with these options, but are there real world benefits?

First, let’s establish that AMSOIL 20W-50 Synthetic Motorcycle Oil is fortified with anti-wear additives to deliver maximum gear wear control. It is also formulated to resist shearing for long service life. The Severe Gear Oils will work just fine, but will not offer improved wear control over the 20W-50 motorcycle oil.

Let’s point out that the AMSOIL Motorcycle 20W-50 and Severe Gear 75W-110 are identical in terms of thickness at operating temperature. Gear lubes use a different viscosity grade scale on the label to prevent confusion between gear lubes and motor oils. Here is the kinematic viscosity of each product at 100 degrees centigrade as shown in centistokes (cST).

20W-50 Motorcycle- 20.4 cST
75W-110 Severe Gear-  20.3 cST
75W-140 Severe Gear- 27.5 cST

Related Reading- Here is a list of our Harley-Davidson articles relating to engine oil, transmission oil, primary oil and oil filters.

Will A Thicker Oil Offer Better Protection In Harley Transmissions?

No that is not the case. The Severe Gear 75W-140 may offer quieter operation simply because of the thicker viscosity. It doesn’t necessarily mean that better wear control is the result. In fact, a thicker oil will generally result in higher operating temperatures.

Bottom Line

AMSOIL 20W-50 Synthetic Motorcycle Oil aces the FZG Gear Test with a perfect score of “zero” wear. Again, it is loaded with anti-wear additives to deliver the ultimate in wear prevention. It is also formulated to limit friction for exceptional shifting performance.  If you wish to use one of the Severe Gear products, that is no problem. The bottom line is that there is no appreciable advantage to using them over the 20W-50. The convenience of using the 20W-50 in all three holes trumps any perceived advantage in our opinion.

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