What happens when enthusiasts looking for greater performance either can’t afford the things that make big power changes, like heads, cam, intake and boost, or have already exhausted use of those items?

The answer is the same, they start looking elsewhere for power.

This—fortunately or unfortunately, depending on the outcome—is also where they resort to the internet for answers. The fortunate side is that the internet is full of advice and even results on what helps make power. People test, people talk, and we are the better for the shared information. The unfortunate side is that said internet is also chock full of opinions and even flat-out falsehoods!

We all want those magic magnets or oil treatments or vortex-generating air intake systems that promise power to deliver on those promises, but the reality is that most of them are long on promise and short on actual delivery. Little things like spark plugs, wires, and even motor oil often tease us with projected power gains, but do they really deliver? Are these areas where you should even be looking for additional performance, or are the gains so inconsequential that your time is best spent elsewhere?

Only one way to find out—quick Batman…to the dyno!

Richard holdener with 2 jugs of engine oil for test
Does synthetic oil really add power, or should you just be more weight conscious? (Image/Richard Holdener)

Testing Performance Benefits of Different Engine Oils & Viscosities

The list of doodads and doohickeys that magically conjure up extra power is endless, but let’s start our day with something simple like engine oil. We all know from those TV commercials that motor oil is “the life blood of any engine.” Your motor, performance or otherwise, won’t survive without it, but is there additional power to be had by choosing a trick and slick racing oil for instance? What about oil viscosity or the age-old synthetic vs. non-synthetic oil conundrum?

When it comes to making more power from different oils, is there any truth there?

To find out, we set up a series of tests, comparing four different oils (technically speaking, five are mentioned). The idea was to run a test mule (in this case a 5.3L LS) first with ordinary conventional oil, then with more expensive synthetic oil of the same weight (3W-30) from Lucas Oil. The idea being to compare synthetic vs. non-synthetic oils to see if a reduction in friction offered by synthetic oil offered any performance advantage, other than oil-life longevity (which it surely adds).

The second test was to compare oil weight. In this case, comparing a lightweight 0W-10 synthetic oil to a much heavier 20W-50 oil.

The Test Motor

Before getting to the results of each test, we need to take a look at our test motor. As stated previously, the test mule was a tried and true 5.3L LS, but not your usual (for us, anyway) iron block, run-of-the-mill base LM7.

This test motor was of the all-aluminum variety, meaning in additional to the usual array of aluminum LS heads, this 5.3L was also sporting the very desirable aluminum block. The all-aluminum L33 5.3L was a big score from a local wrecking yard, and featured flat-top pistons (a la 4.8L), high-flow 799 heads, and a slightly more aggressive cam than the base LM7 5.3L.

Over time, we had changed out the stock cam for a Red Hot cam and matching valve springs from Brian Tooley Racing, along with a FAST LSXR intake manifold and a 102mm throttle body. When combined with a set of 1-7/8 inch long-tube Hooker swap headers with collector tensions, 80 pound injectors and the Holley HP engine management system, this combo was inching closer and closer to the 500 hp mark, with peak numbers over 480 hp (with the right oil).

Our major concern for a test like this was making sure we had a repeatable combo, that produced the same power curve (not just peaks) time after time. This way, we knew that any change in power came from some external change we made (not inconsistency in the engine itself). This motor had proven to be perfectly repeatable, making it the ideal test subject when looking for what might well be minimal changes in output.

Oil Test 1: Mineral vs. Synthetic

The first test involved a comparison between the traditional conventional oil and the premium Lucas synthetic oil. We bought the cheapest oil we could find (we always look for sales) which netted us five quarts of 5W-30 STP conventional oil.

Run with a new oil filter and a 25 to 30 minute break-in and “get acquainted” session, the motor was run with both the conventional and synthetic oils with little or no change in power.

The motor produced 481 hp and 415. lb.-ft of torque.

Oil Test 2: Higher (Heavier) Oil Viscosity

After netting no gains from the synthetic oil test, we turned our attention to testing viscosity, by comparing a lightweight 0W-10 oil to heavier 20W-50 oil. In each instance, we changed the filters, ran the oil for 25 to 30 minutes (loading and unloading the motor) and brought each oil to the same temperature before starting each run.

Unlike the previous test, the oil weight had a significant change in power, with the 20W-50 dropping the peak output by 10 hp to 471 hp at 6,300 rpm. The peak torque dropped to, from 416 lb.-ft. with the 0W-10 oil to 410 lb.-ft. with the heavier 20W-50 oil.

While we would not recommend running either of these oils in your street LS (stick with 5W-30), it is interesting that the heavier oil changed the peak oil pressure by 27 psi and the attending power by 10 hp.

The lesson here…when it comes to oil, don’t go heavy in your Chevy!

oil test dyno result chart
Is there really big power to be had from using the right oil? Well, the reality is there is certainly power to be lost by using the wrong oil, but using the right oil makes as much power as using a trick, lightweight oil. We found this out after running an oil test on our modified 5.3L LS motor comparing a lightweight 0W-10 Racing Oil (from Lucas Oil) to a much thicker 20W-50 (both synthetic). After our test of conventional vs synthetic showed minimal changes in power, we compared these two oils on the BTR-cammed, FAST intake(d) L33 5.3L. The all-aluminum 5.3L had served flawlessly as a test mule for hundreds of dyno pulls and was perfectly repeatable. Run with the lightweight 0W-10 racing oil, the 5.3L produced 481 hp at 6,400 rpm and 416 lb.-ft. of torque at 5,600 rpm. After replacing the lightweight oil with a thicker 20W-50 oil (still synthetic), the power output dropped to 471 hp at 6,300 rpm and 410 lb.-ft. of torque at 5,500 rpm. Run at the same starting oil temp (within two degrees), the peak oil pressure jumped by 27 psi from 67 to 94 psi. (Image/Richard Holdener)
5.3L Casting mark on an aluminum gm ls engine block
Our test motor started out life as an all-aluminum, junkyard L33 pulled from a local wrecking yard. (Image/Richard Holdener)
799 casting marks on a gm ls engine cylinder head
Always a desirable find in a junkyard, the aluminum L33 featured higher compression, a slightly more aggressive cam, and the high-flow (LS6-style) 799 heads. (Image/Richard Holdener)
btr camshaft in box
From previous testing, the L33 test mule was equipped with a BTR Red Hot cam that offered .617/.619 lift split, a 221/22X duration split and 113 LSA. (Image/Richard Holdener)
ls engine with valve cover removed to show valvetrain
The cam upgrade from Brian Tooley Racing required a matching valve spring upgrade, though the rockers remained factory stock with no trunnion upgrade. (Image/Richard Holdener)
ls engine on dyno with fast intake manifold
Working with the high-flow 799 factory heads and BTR cam upgrade was a fast LSXR intake manifold. In the sub-7,000 rpm range on an LS, the FAST is difficult to beat for average power production. (Image/Richard Holdener)
102mm throttle body on an ls engine on dyno
The FAST LSXR intake featured a 102mm throttle opening so we saw no reason not to utilize the maximum airflow potential of the intake with a matching 102mm throttle body. (Image/Richard Holdener)
exhaust headers n an ls engine dyno
The exhaust system consisted of a set of 1-7/8 inch, long-tube Hooker headers feeding collector extensions. (Image/Richard Holdener)
close up of wire loom on an ls engine
To ensure plenty of fuel flow to the modified 5.3L motor, we replaced the stock L33 injectors with these 80 pound fuel injectors from Accel. (Image/Richard Holdener)
richard holdener at engine dyno control room
Rather than rely on the factory ECU, we dialed in the AF and timing curves on the 5.3L using Holley HP management system. (Image/Richard Holdener)
meziere water pump on a gm ls engine
The usual arrangement when running these junkyard LS motors on the dyno is to replace the factory accessories with a simple Meziere electric water pump. (Image/Richard Holdener)
Oil pressure gauge on an engine dyno run panel
Naturally the oil pressure was monitored and data logged for each run. I do like having a mechanical gauge to verify the actual oil pressure during each run. (Image/Richard Holdener)
ls engine on dyno for test run
For each of our oil tests, the modified 5.3L was run on the dyno with the same AF and timing curve, as well as identical oil and water temperatures. (Image/Richard Holdener)
quart jug of of stp motor oil on table
Our first test involved typical off-the-shelf conventional engine oil vs. premium Lucas synthetic oil. (Image/Richard Holdener)
used engine oil pouring into drain pan
After running each of the different oils, we drained the oil (and changed the filter), then subjected each new oil to a solid 30 minutes of run time before each test. (Image/Richard Holdener)
quart bottle of lucas synthetic engine oil
After running the ordinary 5W-30 STP oil, we replaced it with 5W-30 Lucas Synthetic oil. We saw little if any change in power, but the real gains from any synthetic include longer oil life and therefore improved protection. (Image/Richard Holdener)
quart bottle of lucas racing oil
After comparing the basic oil to the premium stuff, we decided to see if there was anything to be gained from a viscosity change. We started the test with lightweight, 0W-10 Synthetic oil from Lucas. (Image/Richard Holdener)
5 quart jug of lucas engine racing oil
We compared the 0W-10 oil to some thicker 20W-50 oil. To be clear: We would recommend neither of these weights for your street LS, stick with 5W-30. (Image/Richard Holdener)
man pouring oil into an engine on a dyno
After pouring in the thicker oil, we definitely saw a change in both the oil pressure and power on the test motor. (Image/Richard Holdener)

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Richard Holdener is a technical editor with over 25 years of hands-on experience in the automotive industry. He's authored several books on performance engine building and written numerous articles for publications like Hot Rod, Car Craft, Super Chevy, Power & Performance, GM High Tech, and many others.