Everything in Balance

When it comes to modern engines and driving, oil temperatures are a balancing act between hot and cold; thin and thick.  When straight-weight oil, also known as single-weight oil (like SAE 30), is cold, it’s thicker and more viscous.  Higher viscosity means that the oil flows slowly and sticks to surfaces longer.  This also means, however, that on cold start-up, it’s much harder for the engine to move the oil and thus bearings and wear surfaces don’t always get the oiling they need until the engine warms up.  Oil that is too thick in cold conditions greatly increases engine wear and makes it harder for the engine to start.

The modern solution to reduce engine wear on cold start-up, while maintaining proper oiling when at operating temperature, is mixed-weight oil.  This is the oil you normally find on your auto-parts store shelves with a number such as 5W-30 on the bottle.  That “W” in the middle stands for “winter” and denotes how easily the oil flows in cold conditions.

Mixed-weight oil starts out life as a straight-weight oil. In order to make the oil mixed-weight, viscosity-improving additives are then introduced. These additives allow the oil to remain viscous at higher temperatures, keeping the bearings and other wear surfaces lubricated.  Put simply, a 5W-30 oil flows like an SAE 5 (very thin) oil in cold conditions, but maintains the viscosity of an SAE 30 (thick) oil once the oil reaches operating temperature.  Mixed-weight oil allows lubrication to reach the bearings and wear surfaces of the engine quickly when cold and stay there when at operating temperature.

A Thinning Issue

So, what does all of this have to do with Mishimoto and your Camaro SS?  Well, it all comes down to the second number on the oil’s bottle.  The engineers at GM carefully crafted the LS3 and L99 engines’ tolerances to play nicely with 5W-30 oil.  What’s most important about the “30” is that the viscosity is measured at 210°F.  As we’ve determined, oil thins and becomes less viscous as it gets hotter.  While the Camaro’s engine is happy with a 30-weight oil at 210°F, at temperatures above 210°F those viscosity-improving additives we talked about earlier begin to lose their effectiveness.

As oil temperature begins to climb into the 290°F range, the oil in the engine begins to “shear” down closer to a 20-weight oil or less. As this happens, the bearing and piston clearances are no longer filled with effective oil.  GM’s engineers planned for the eventuality that their vehicles would be driven hard and oil temps would climb above 210°F, but there’s only so much they could do.  That’s where Mishimoto comes in.

Heating and Cooling . . . and Heating

Mishimoto is excited to share that we’ve begun the process of designing an oil cooler for the 2010-2015 Camaro SS.  Now that we’ve gotten the scary technical realities out of the way, let’s look at the Camaro’s stock oil cooler and how we plan to improve on that system.

The stock oil cooler on the 5^th Gen Camaro SS is a common, liquid-to-liquid design that utilizes the engine’s coolant to regulate the oil’s temperature.  This system serves two purposes: to heat the oil to operating temperature quickly, and to cool the oil to the temperature of the coolant once the engine is at operating temperature.  The first half of that process is a very important one.  The engine’s coolant heats up much faster than the oil would on its own.  This is another measure, on top of mixed-weight oil, that allows the oil to flow throughout the engine quickly on cold starts and reduce engine wear.

The second half of the stock oil cooler process is where it tends to fall short.  To save weight, time, and money, manufacturers utilize the already-existing heat exchanger that is the car’s radiator to perform the work of cooling both the oil and the coolant.  While oil does not directly flow through the radiator, the coolant and oil both flow through separate chambers of the oil cooler.  From the oil cooler, the coolant carries heat away from the oil and dissipates it through the radiator (if all of this is a little hard to follow, check out the diagram below for a visualization of how the stock system works). While this may sound like a simple and efficient means of regulating oil temperatures, the stock oil cooler has its advantages and disadvantages.

Pros and Cons

One advantage, as we discussed earlier, is that the coolant heats the oil much faster than it would just circulating through the engine.  It also means that the oil remains at operating temperature throughout normal driving, keeping wear surfaces properly lubricated.  The main disadvantage, however, appears when the engine is pushed beyond normal driving conditions.

At the track or during spirited driving, or even just sitting in traffic, the coolant temperature can increase beyond 210°F, the temperature at which the oil viscosity is tested.  The main purpose of coolant is to carry heat away from the head, block, and cylinders of the engine to prevent damage.  Problems occur when the stock radiator and oil cooler cannot dissipate the heat generated by the engine.  That is where a standalone oil cooler comes into play.

Plan for the Worst, Cool like the Best

For the 5^th generation Camaro SS we plan to retain the factory liquid-to-liquid oil cooler but also introduce a liquid-to-air oil cooler, similar to the factory radiator.  Incorporating the stock oil cooler will mean that the oil will still warm up quickly and should make cold starts as easy on the motor as stock. Once the oil warms up, the Mishimoto oil cooler will take over the duty of cooling the oil within operating temperature.

We plan to mount our oil cooler behind the grill for maximum air-flow and efficiency, while still leaving room for forced-induction intercoolers.  In order to tap into the flow of oil, we will be incorporating an oil filter sandwich plate to divert oil into the cooler. To help regulate the oil temperature once hot, we will be offering the oil cooler with both a thermostatic sandwich plate, for those who will both daily-drive and race their cars; as well as a non-thermostatic sandwich plate, for those who plan to primarily race their cars.  Finally, as with all of our direct fit oil coolers, this kit will be bolt on, with everything you need to install and go (except oil).

There’s nothing quite like the feeling of powering down the long straight, your right foot trying to turn the throttle into dust, hurtling towards the first turn. As the engine RPM climbs into the red you tell yourself not to lift, keep that foot down until the last second. You’ve put your heart and soul into your Camaro’s engine, and you’ve placed your trust in your Mishimoto oil cooler. All you need to do now is keep your foot down and let them both do their jobs.

Combating high oil temperature is something that almost every 5th Gen Camaro SS owner has experienced. The factory liquid-to-liquid oil cooler that we examined in the last post is just not up to the task of cooling the engine’s oil during high-stress driving, or even idling in traffic on a hot day. For the past couple of months, our project engineer, Jason, has been working on a direct-fit oil cooler that will let the Camaro run cooler, even if your palms get a little sweaty behind the wheel.

Let the Work Begin

Deciding where to begin starts with pulling the front bumper off the Camaro. Once the large bumper was peeled off, we found a cavernous amount of space to work with. While the core that we planned on using was only 11” by about 7”, we wanted to be sure that it was positioned to allow the use of a front-mount intercooler for turbo and supercharged vehicles, as well as keeping it in the flow of air through the bumper. The most important goal remained, which was finding a way to mount an oil cooler that doesn’t require drilling or modifying the body of the vehicle. With all of this in mind, our options quickly became limited.

Most front-mount intercoolers mount low, utilizing airflow through the large opening at the bottom of the bumper and take up a lot of space laterally. That left only the space above the crash bar (the large rectangular beam in the photo above). Luckily, the 5th Gen Camaro’s aggressive, open grill provides ample air-flow through the upper half of the front end as well, so we had some space left to work with. All that was left was to find a place to mount a bracket without drilling or cutting. As if Chevy knew we were going to need a place to mount an oil cooler, the upper radiator support provides two perfect, already tapped holes, right in the center of the grill where the air flows through. With the proper measurements taken, Jason was ready to start working up the model for the oil cooler core bracket.

One of the greatest advantages to making our own oil cooler cores is that we can design them with easy mounting options in mind, allowing us to transfer one core from one vehicle to another simply by creating a bracket. This interchangeability also lets us design the simplest possible bracket for each application. One major consideration when mounting an oil cooler is to make sure that the inlet and outlet fittings have ample room above and beside them. For this bracket and core, the fittings extend from the top, meaning space above the core was paramount. Jason was able to design a simple L-bracket that dropped the oil cooler down just far enough to clear some 90° AN fittings. A Mishimoto M-logo adds a subtle badass touch to a relatively simple piece. Once the bracket design was finalized, Jason sent the model off to our fabricator to be cut out on the waterjet, bent, and painted.

Connecting Point A to Point B

With the mounting of the oil cooler core sorted, the next step in cooling the Camaro was getting the core filled with oil. There are a few ways to tap into the oil source of an engine and returning the cooled oil. The most common methods are tapping into existing oil galley plugs on the motor, using one of those galley plugs for the cooler’s oil source and tapping the oil pan for the return, or using a sandwich plate between the oil filter and engine. Each method has its advantages and disadvantages. Galley plugs are often hard to get to, require special fittings or thread adapters, and unless you know the layout of the oil galleys within the motor, you can’t be sure how much of the engine is actually getting the cooled oil. However, this method is pretty simple and leaves few possibilities of failure. Using a galley plug for the source of the oil and dumping the cooled oil back into the pan is more effective in ensuring most of the motor sees the cooled oil, but it requires draining the oil pan, removing it, drilling and tapping a hole or welding on a bung, cleaning the pan and then reinstalling it. When there’s no other option available, this method works well and it’s reliable, but we prefer the third option: the sandwich plate.

Sandwich plates do exactly what their name suggests; they sandwich between the oil filter and its mount to tap into the engine oil as it enters the filter. Sandwich plates are a simple, bolt on solution to tapping into the engine oil without a lot of extra parts or fabrication. There are a few important considerations to make when using a sandwich plate, however. First, it’s important to use a quality plate with quality seals to prevent leaking between the plate and the filter mount and between the plate and the filter. Our plates are made with the same high-quality materials as all our components and include a square O-ring between the plate and filter mount, so you have the most possible sealing surface area.

It’s a Little Tight in Here

The other major consideration with a sandwich plate is ground clearance. For vehicles with a low-mounted oil filter, a sandwich plate will push the filter closer to the ground. For some vehicles, this may push the oil filter lower than the protective sub-frame of the car, making it susceptible to road debris and scraping over large bumps. One must consider clearance for any under-paneling on the vehicle as well. This is an especially important point for daily-driven vehicles that see road surfaces that are a less predictable than tracks. We obviously want our oil cooler kit to be functional on both daily-drivers and track cars, so we paid close attention to ground clearance as we installed our sandwich plate on the Camaro SS. Luckily, with a thickness of only about 1.25 inches, both the thermostatic and the non-thermostatic sandwich plates kept the oil filter above the sub-frame. With major structural components of the sub-frame both in front of and beside the oil filter, we’re confident it will stay safe.

The final piece of the puzzle was to connect the sandwich plate and the oil cooler. For most of our oil cooler kits, we utilize sturdy and durable stainless steel braided lines and AN fittings. We did the same with this kit, but the Camaro SS presents some unique challenges in terms of clearance for lines and fittings. We chose this particular SS for one popular reason: it was equipped with long-tube headers. While long tubes sound amazing, and produce a ton of power, they also take up a ton of room. With the main collector of the driver-side header passing within inches of the oil filter location, our choice of fittings for the sandwich plate needed to be as compact as possible. Instead of using 90° AN fittings for the sandwich plate, we used banjo fittings that could sit flush to the plate and direct our lines towards the front of the car. Jason ran the lines through a safe route over the sub-frame and into the front bumper area to connect to the core.

Performance >= Beauty

Two days of measuring, designing, measuring some more, testing and fitting led to a successful installation of our prototype oil cooler kit. Jason was happy with how it turned out considering all the challenges he faced with limited clearance and a laundry list of requirements. But it’s not enough for our products to look the part, they have to function even better than they look. With a few modifications to the lines to accommodate temperature and pressure sensors, Jason buttoned up the Camaro and hit the road for some performance testing. We were lucky enough to have an unseasonably warm day in the Delaware winter to test the cooler. Of course, I had to ride along to man the laptop; it was a pretty rough day in the office. With an open highway in front of us, Jason leaned his right foot into the throttle, bringing the LS3 to a screaming pace and pushing us into our seats under its 400 ft-lbs of torque. After a few repetitions and the usual I-95 traffic, the cooler showed no signs of suffering from heat-soak so we headed back to the shop for Jason to crunch the data.

The stock liquid-to-liquid oil cooler on the Camaro kept the oil at around 200°F under similar conditions. Keeping in mind that we were not driving anywhere near as hard as one would on the track, this test goes to show just how ineffective the stock oil cooler is. With the addition of the Mishimoto oil cooler, Jason was able to lower the oil temp by almost 40°F with an average oil temperature hovering around 160°F at the oil cooler outlet. This 25-row core should prove more than efficient enough to bring those 230°F+ oil temps at the track down to something a little less heart attack inducing.