Technical Tip: Recommended Oil for 2010 9-5
Saab Cars North America has updated its oil recommendation for the 2010 9-5. The original specification called for 5-30 Mobil 1. The new recommendation allows for the following: GM LL-A-025 requirement with a viscosity of 0W-30, 0W-40, 5W-30, or 5W-40. This means that the current Mobil1 used in the 9-3 and previous 9-5, 0W-40, is now approved for use in the new 9-5 and will be the oil fill here at Charles River Saab.
Technical Tip: Octane
The question of which octane to use often comes up here, especially these days. There are lots of myths about octane and the advantages of higher octane and the disadvantages of lower octane fuel. Before we go further, it is important to understand what octane is. Higher octane does not make a fuel premium, other than in price. Other than the octane difference, there is no difference between grades, and none is better in any other way than the others. Octane is one of many additives in gasoline. Its purpose is to supress ignition of the fuel. It may seem odd that an ignition supressor would be a good thing in gasoline, but what it prevents is unintended, or premature ignition that occurs with heat and compression of the air-fuel mixture in the engine. This is “pinging” or “knocking” that, once upon a time, we could cure with higher octane. This would typically occur in engines with higher rates of compression of the air-fuel mixture, and the higher the compression of a gas (think back to your physics class), the higher the temperature. Therefore, low compression (and low performance) engines require low octane, high compression (high performance) engines require high octane. Simple, right?
What about a turbo-charged Saab, though? When driven normally your Saab’s engine has modest compression. However, when accelerating, the turbo pumps extra air into the engine, effectively raising the compression. The suggested octane for a Saab may be as high as 93, yet I am here to tell you that down to 87 is fine. How? Why? Simply put, your Saab has a sensor to detect knock/ping. What makes your Saab special is that it has two ways of adjusting the engine when ping is detected. First, it can adjust the timing of the spark. Then, it can adjust the amount of turbo boost so that no matter what grade of fuel you run, the Saab Trionic engine management system will optimize settings for the fuel. So, if you run high octane, you will get more performance. Run 87, you will run safely and with less available performance. My suggestion–try the 87, see if the performance is adequate for you, and if so stay with it. If not, try something higher. There is no adjustment period, just refuel and go!
Technical Tip: Wheel Alignment
What is wheel alignment? We all know that it’s a good thing to have done to our cars, that it corrects pulling, corrects a steering wheel that is not pointed straight, prevents tire wear, and minimizes rolling resistance. A common misconception about alignment is that it will repair vibration or shimmy in the steering; those symptoms are caused by wheels or tires, not by alignment. Technically, wheel alignment is the orientation of the wheel and suspension relative to the chassis, and to the other wheels. Alignment can be measured from three perspectives: toe, camber and caster. Toe is the most common adjustment. To understand toe, think of your feet. All cars have toe-“in”, at least on the front wheels. So looking at your feet, start with your feet being straight, and then move the front of your feet so they are closer together than your heels (pigeon toed). You now have toe-in! Unlike you, a car is very unstable without toe-in and tends to wander and drift. The toe-in will create some mild tension, with each wheel pushing gently towards the center, thus the car tracks straight and feels more secure. Most cars today have toe-in at the rear also, but that wasn’t always the case, though Saabs, even when they had solid-axle rear suspension had rear toe-in, which added to their secure handling and solid feel.
Next is camber. Camber is the lateral orientation of the wheel to the chassis. Going back to your body, if your legs are straight from the knee down, think of that as neutral camber. If you are bow-legged, you have positive camber. If you are knock-kneed, this is negative camber. While camber is difficult to discern on the front wheels, rear wheels often have a more exagerated camber, especially when heavily laden. Most cars have negative camber (wheel in at the top). The purpose of negative camber is to enhance cornering grip. Think of a skier, putting weight on the inside edge of the outer ski on a turn.
Last is caster. Caster doesn’t define the orientation of the wheel at all, but rather axis between the top of the suspension and the wheel. The purpose of caster is to provide stability and to cause the steering wheel to return to center when released after a turn. This is also what makes the steering completely unstable in reverse, with the steering wanting to go not to center but to the steering lock in one direction or another. Think of the casters on the front of a shopping cart. The wheels trail behind the swivel mechanism when going forward. If you pull the cart rearward, the casters will swing 180 degrees. In a car, the caster can’t swing 180 degrees, but it will swing as far as it can–to the steering lock.
Technical Tip: Fuel Mileage
The most significant contributor to good or bad fuel mileage is the driver. I have noted in my commute that I can affect an increase in fuel mileage of almost 50% if I pay close attention. The best way to gauge how your driving habits contribute to your fuel economy, make a habit of always having the average fuel consumption displayed on your dash. Then, reset it every day at first and see what conditions move that number up and down. The presence of mind about fuel consumption alone will likely start to amend your habits right away. The old adage about driving like you have an egg on the accelerator is a good one; rate of acceleration has a huge effect on consumption. You’ll also find that braking as little as possible, through good planning, also conserves fuel. Try turning off the air conditioning (or use ECON) and see the gains that provides. Finally, you’ll really see the difference that speed makes on the highway. It all starts, though, with watching the mileage indicator and having reset every time you drive!
Technical Tip: Spring Cleaning
If your car is parked among trees, it is likely that if you open your hood you will find a nice pile of leaves or pine needles on the cowling under the hood at the base of your windshield. As the weather warms up and winter snows are replaced by rain, the last thing you want to have happen is for these leaves to decompose and fall through the grill into the bulkhead which houses your heating/air-conditioning and ventillation systems. Once there, that detrious can bring all sorts of havoc to bear, including growth of microbes in your ventillation, and even causing flooding in the car by prohibiting air conditioning condensate from flowing freely through the condensate evacuation hoses. Just remove all those leaves, and then with a flashlight look through the grill to see if there is any accumulation of debris in the bulkhead. If there is, and if you want to remedy this yourself, you will need to remove the wiper arms (you’ll need a very small flat blade screw driver to remove the covers on the wiper arms, and then a socket 12-15 mm to remove the nuts depending on your car). Then remove the clips holding the plastic cowling in place and lift off the cowling. A shop vacuum is perfect for this. If the fresh-air filter is soiled, you can replace that, too, while you’re in there.