AMSOIL vs Polaris vs Mobil 1 - Which oil is best for ATVs/UTVs?

As an ATV/UTV owner and enthusiast with decades of experience in automotive engineering, I can't stress enough the importance of choosing the right oil for your vehicle. Whether you're tackling tough terrain on your Polaris RZR or hauling heavy loads with your Ranger, the oil you choose plays a crucial role in your machine's performance, longevity, and reliability.

In this comparison article, we'll stack up technical specs between AMSOIL's ATV/UTV oils, Polaris's own PS-4 and AGL oils, and Mobil 1's most-used motor oil for ATVs & UTVs. As someone who has worked extensively with various oils and seen their effects firsthand, I aim to provide you with clear, unbiased information to help you make the best choice for your ATV or UTV.

Understanding ATV/UTV Oil Requirements

Before we jump into our comparison, it's crucial to understand the unique demands placed on ATV and UTV engines. These vehicles often operate under extreme conditions that passenger car engines rarely encounter:

1. High-temperature operation: ATVs and UTVs frequently run at high RPMs for extended periods, generating significant heat.
2. Cold starts: Many of these vehicles are used in cold climates and may sit for long periods between uses.
3. Dusty and dirty environments: Off-road use exposes engines to dirt and debris, which can accelerate wear if not properly protected against.
4. Heavy loads: UTVs, in particular, are often used for hauling and towing, putting extra stress on the engine.
5. Varying speeds: From slow crawls over obstacles to high-speed runs, these engines need to perform across a wide range of operating conditions.

Given these demands, the key factors in choosing the right oil include:

• Viscosity: The oil must maintain proper thickness across a wide temperature range.
• Additives: High-quality additives are crucial for wear protection, oxidation resistance, and maintaining engine cleanliness.
• Synthetic vs. Conventional: Synthetic oils generally offer superior performance in extreme conditions.
• Manufacturer recommendations: It's important to consider what the vehicle manufacturer specifies for warranty purposes.

In the next sections, we'll dive into a detailed comparison of these oils, examining their performance in various aspects crucial to ATV and UTV operation. This will help you understand how AMSOIL stacks up against Polaris's own oils as well as other leading competitors.

Comparative Technical Analysis

AMSOIL ATV/UTV 5W-50 vs. Polaris PS4 5W-50

Let's dive into a head-to-head comparison of AMSOIL's 5W-50 Synthetic ATV/UTV Engine Oil and Polaris PS-4 5W-50.

Viscosity Ratings: Both oils are 5W-50 grade, which means they flow like a 5-weight oil in cold temperatures and maintain the thickness of a 50-weight oil at high temperatures. This wide range is crucial for the varying conditions ATVs and UTVs encounter.

‍

Unfortunately, Polaris doesn't publicly disclose much data for their PS4 oil. This lack of transparency can make it difficult for you to make informed decisions. Of the two specs they've provide, AMSOIL indicates a better flash point rating yet Polaris PS-4 5W-50 does show a slightly better kinematic viscosity @ 40 degrees C, slightly suggesting it has better cold-start protection & performance. But that is likely at the expense of high-temperature protection and quicker oil degradation.

AMSOIL's pour point of -48°C which is excellent for cold weather starts.

Polaris Performance Testing

AMSOIL ATV/UTV 5W-50 Engine Oil was installed in a 2018 Polaris Ranger and exposed to extreme operating conditions in AMSOIL's mechanical lab. The speed was held at 45 mph with the throttle wide open, pushing the engine and transaxle it their limits.

‍

‍

After 100 hours and 4,000 miles of torture, the engine and transaxle were torn down, revealing like-new pistons, cylinders, cams and transaxle gears.

AMSOIL ATV Transmission Oil vs. Polaris AGL

Now let's compare AMSOIL's Synthetic ATV/UTV Transmission & Differential Fluid to Polaris AGL.

‍

The vast difference in kinematic viscosity @ 40°C suggests that the AMSOIL Transmission Fluid is a heavier weight oil, in the SAE 75W-90 or 80W-90 range for gear oils vs. the Polaris AGL likely being in the SAE 75W or 80W range.

This is a clear indicator that the AMSOIL fluid will provide a thicker film and much more protection at operating temperatures, especially under heavy loads.

‍

AMSOIL ATV/UTV Oil vs. Mobil 1 Racing 4T Oil

Many ATV/UTV'ers use and recommend Mobil 1 Racing 4T motor oil, although marketed as a 4-stroke motorcycle oil, similar operating conditions exist in 4-stroke powersports vehicles like ATVs & UTVs. We'll compare their 10W-40 with AMSOIL's 10W-40 ATV Oil. For a more thorough breakdown of AMSOIL motor oils vs. Mobil 1, visit this article.

‍

Of the ATV/UTV oil specs that both AMSOIL and Mobil 1 publicly list, AMSOIL has better ratings for viscosity index, flash point, and kinematic viscosity @ 100°C.

The higher viscosity of the AMSOIL ATV oil at 100°C suggests it provides better protection in high-temperature, high-stress situations common in most ATV/UTV use.

AMSOIL's higher flash point also indicates potentially better high-temperature stability.

Mobil 1 has a lower pour point which suggests superior cold-start capabilities.

Cost Comparison - AMSOIL vs Polaris vs Mobil 1

5W-50 ATV/UTV Oil Price Comparison

Product	Relative Price
AMSOIL 5W-50 ATV Oil (Regular)
AMSOIL 5W-50 ATV Oil (Preferred Customer)
Polaris PS-4 Full Synthetic

10W-40 ATV/UTV Oil Price Comparison

Product	Relative Price
AMSOIL 10W-40 (Regular)
AMSOIL 10W-40 (Preferred Customer)
Mobil 1 Racing 4T 10W-40

ATV/UTV Transmission/Gear Oil Price Comparison

Product	Relative Price
AMSOIL ATV Transmission Fluid (Regular)
AMSOIL ATV Transmission Fluid (Preferred Customer)
Polaris AGL

‍

From all the oil comparisons we've made in this article, AMSOIL's Preferred Customer prices are comparable to or cheaper than these competitors, making it the best choice for those of you who want to maximize performance and protection in your ATV/UTV and get the most bang for your buck.

Is AMSOIL the best ATV oil?

AMSOIL ATV/UTV oils consistently outperform or match competitors in key areas such as viscosity stability, high-temperature protection, and wear resistance. While "best" can depend on specific needs, AMSOIL demonstrates superior performance in many crucial aspects of ATV/UTV operation.

Is AMSOIL good for Polaris RZR?

Yes, AMSOIL is an excellent choice for Polaris RZR. Our comparison details AMSOIL's performance in extreme testing conditions using a Polaris Ranger, showing exceptional protection for engine components and transmission gears. AMSOIL's 5W-50 formulation is specifically designed to meet the demands of vehicles like the Polaris RZR.

What oil does Polaris recommend?

Polaris recommends their own PS-4 5W-50 Full Synthetic oil for their ATVs and UTVs, including the RZR models. However, our technical comparison demonstrates that AMSOIL's 5W-50 ATV/UTV oil meets and exceeds Polaris PS-4's performance in the metrics where data is available, offering superior protection and performance at a cheaper price.