Located in one or both of the valve covers, allows excess crankcase pressure to circulate back in to the intake to be burned.

Service Interval: 25k, sometimes never (inspect only)
Many may last indefinitely, many do not have suggested service intervals, some vehicles do not have typical PCV valves at all. A proper PCV typically has a metal ball inside it that will rattle when the PCV valve is not stuck closed. Just because it rattles does not make it good, however.

Why do we replace/service:
Over time, the one way check valve may stick, usually in the closed position. This allows the crankcase pressure to build up.

What happens if we don’t service:
Excess crankcase pressure that builds up can cause multiple oil leaks from many different places. This is probably the #1 cause of oil leaks in car engines today.

General Recommendations:
This is an inexpensive part that can cause lots of money in potential repairs.

Service Interval: 5-6k miles for rotation, Every month for air pressure checks
If you notice uneven tire wear, an up and down pattern along the tread, or outside edgewear, it may be time (or past time) for a tire rotation. With radial tires, and especially with lower profile radial tires, it is difficult to determine air pressure simply by looking at the tires. A tire may look the same whether it has 15 psi or 50 psi in it – the only way to truly check is with a proper air gauge.

Why do we replace/service:
To promote long tire life and prevent uneven wear.

What happens if we don’t service:
Tires may wear unevenly and cause damage to the tires. If a tire is run even a few psi low, it will wear faster, not handle as well, reduce fuel mileage and if ran that way long enough can cause irreparable tire damage. If a regular rotation schedule is not followed, tires may start to cup or feather (when the tread blocks become uneven and have one side higher than the next). This causes excessive noise from the tires. Also, depending on the drive configuration of the car, the drive tires may wear faster.

General Recommendations:
On average, a tire may lose 1 psi per month, and when the temperature changes, may lose 1 psi per 10 degrees change cooler, or vice versa. This can be reduced by using nitrogen in tires, however a tire filled with nitrogen will still lose pressure through typical punctures or leaks and should still be checked monthly. Rotations are not possible with all cars. Vehicles with staggered fitments front and rear may be left to only rotate side to side. This is not very easy with directional tires and on those vehicles, it may be recommended to use asymmetrical tires so that this is possible.

How the wheels and tires are positioned and angled, relative to the cars chassis.

Service Interval: 6 months – 2 years
Many manufacturers do not specify an interval for alignments. Many cars are not really well aligned, even from the factory. Some obvious cues for an alignment being required are the car pulling one way or the other, an uneven steering wheel and uneven tire wear. The types of roads, driving style, and quality of roads driven on all have an impact on how often an alignment should be performed.

Why do we replace/service:
To ease the driving experience, minimize tire wear and minimize wear on suspension components.

What happens if we don’t service:
Left unchecked, a bad alignment can cause uneven and accelerated tire wear, costing potentially more than an alignment would have cost. It can also cause wear and undue stress on the vehicles steering and suspension components.

General Recommendations:
It is very hard to get an absolute perfect alignment, but that is ok, it doesn’t have to be absolutely perfect for good tire wear and to avoid a pull one way or the other. Excessive camber (the upper part of the tire leaning in) can lead to tracking the road and wear on the inside edges. Toe is the number 1 tire wear angle and it is very important it get as close as possible to the exact specification. Caster is an angle that only affects the front tires. It is how much the wheel leans back, similar to a motorcycle. Caster is an angle that can cause a car to pull if it is not correct, and excessive caster leads to better high speed stability, but more steering effort.

Lubricates the internal engine components, transfers heat and the filter keeps the oil clean.

Service Interval: 3k-15k, 6 months – 1 year
For many years, the general advice was to change the oil every 3k miles or 3 months. With advances in engine and oil technology, these suggested intervals have grown. Many, if not most vehicles, have a suggested service interval of 5k, and some oils suggest service intervals as high as 15k or more. Undeniably, lots of money is spent unnecessarily on oil changes that are not required at the time. Unfortunately, the only way to really tell how much longer oil is safe to use is to send it in for a used oil analysis. The problem with this is that it costs just as much for the analysis as most oil changes cost. It is also suggested to replace oil every 6 months or 1 year as well, regardless mileage. Aside from a used oil analysis, it is impossible to tell how dirty oil is just by its looks. Some oils are very dark even when brand new.

Why do we replace:
Over time, oil breaks down. Some oil will seemingly last forever without breaking down, however over time it becomes contaminated and the detergents and additives are diminished. The contamination is caused by wear of the cylinder walls, bearings, and blow by, which includes combustion gases and unburnt fuel.

What happens if we don’t service:
As the oil breaks down and the additives are not able to keep the oil passageways clean, the oil will start to solidify, or become sludge. This leads to poor lubrication and wear on the engine surfaces – cylinder walls and bearings take the worst of it, and of course, they are also the most important. As time progresses, the engine will start burning more oil and the additional wear on the engine will cause lower oil pressure, which will lead to a catastrophic failure.

General Recommendations:
There are many choices in oil. The type of oil to use is a personal preference. For the most part, so long as oil change intervals are followed, you should have no problems. There are also many different weights of oil. The builder of your car knows best and their suggestions should be followed as far as the weight of oil to use. Many think that higher mileage engines require heavier weight oils. In general, this is not true unless the engine is burning a lot of oil. By using heavier weight oil, you increase oil pressure, but lower the amount of oil that flows through the engine. In modern engines, flow is more important than pressure.

Throttle body cleaning, intake manifold cleaning, fuel system treatment.

Service Interval: 15k or more
Society of Automotive Engineers claim that service intervals of 15k miles may be beneficial to the vehicle. Many vehicles have no suggestion for this service at all.

Why do we replace/service:
EGR and PCV systems allow combustion gases and contaminants to enter the intake tract. These are typically dirty, oily gases which accumulate over time on the throttle plate, walls of the intake manifold, injector nozzles and the backside of the intake valves. Servicing cleans the throttle body and adds a detergent into the vacuum line system while the vehicle is running, in order to clean the intake manifold and valves.

What happens if we don’t service:
Over time, the build up causes decreased fuel mileage and can cause odd idle problems and poor power delivery. Left unchecked, other failures in the EGR system and sensors inside the throttle body may cause severe drivability concerns.

General Recommendations:
The better quality of fuel you run, the less you may need to do this service, as valves generally stay cleaner with higher quality gasolines (higher quality, not higher octane). Regardless what type of fuel you use, the gases from the EGR and PCV system will still accumulate on the throttle plate and intake manifold (they are before the injectors).

Also known as an A/C filter – is the equivalent of your home air conditioning units filter, but for your car. Filters the air as it passes through the air conditioning (and heating) system.

Service Interval: 30k-50k
Pretty straightforward here, the more you use the heating and cooling system, the more contaminants are caught here. You can remove the filter and look at it, though flow may be restricted even with a clean appearing filter.

Why do we replace/service:
Just like your home unit, this filter gets dirty and reduces system performance.

What happens if we don’t service:
Air flow through the system is restricted and the system does not work as efficiently. In severe cases, enough resistance to air flow over time can cause the fan motor in the system to burn out.

General Recommendations:
It is nice to breathe clean air and keep the system performing as new. This is a simple way to maintain that.

Typically in a black box next to the engine, under the hood. Keeps the air entering the engine clean.

Service Interval: 12k-30k
Air filters may become restricted with dust and still look relatively clean. Simply knocking the dust out of it does not help this matter.

Why do we replace/service:
Keeps your engine running as efficiently as possible, the better your engine can take air in, the more efficient it can be.

What happens if we don’t service:
Idle may become rough and random, fuel economy may decrease significantly. The Lexus engine may not start or may need excessive cranking to get it started, eventually it can cause problems with the proper air to fuel ratio and cause other failures in the fuel system.

General Recommendations:
Change your air filter every fourth or fifth oil change, perhaps more often if you live in a desert/dusty environment or a large city. Never run without an air filter, with an air filter with a hole in it, or one that does not seal properly – even small dust particles can cause added wear inside an engine and also contaminate the oil. Some manufacturers, such as K&N, offer air filters that never require replacement, only cleaning periodically.

Service Interval: 15k-100k, some vehicles, never (inspect only)
Service Interval varies greatly depending on the type of driving you do. Under extreme conditions, some vehicles actually call for every 15k miles, while under normal driving conditions, some never suggest fluid replacement. To inspect, check fluid levels based on your vehicles configuration. Breakdown of the fluid may not be apparent, but if the fluid is notably dirty, it should be replaced.

Why do we replace/service:
As with any other fluid in a vehicle, the heat and friction created causes the fluid to break down over time.

What happens if we don’t service:
As fluid wears, added wear inside the transfer case is happening as well. A little more complex that differentials, there are moving pieces, sensors and sometimes chains that require proper lubrication.

General Recommendations:
Although some manufacturers do not suggest replacement ever, a transfer case fluid replacement may be cheap insurance to protect a somewhat pricey part. Follow your manufacturers recommendations for fluid weight and pay attention – some may require synthetic gear oil.

Attached to your transmission (in FWD cars) and is in the center of the drive axle in RWD cars. 4WD/AWD vehicles will have differentials in the front and rear, as well as a center differential and/or transfer case.

Service Interval: 12k-30k, some vehicles, never (inspect only)
Service Interval varies greatly depending on the type of driving you do. Under extreme conditions, some vehicles actually call for every 12k miles, while under normal driving conditions, some never suggest fluid replacement. Some FWD vehicles include the differential fluid as part of the transaxle fluid. To inspect, check the fluid level. Breakdown of the fluid may not be apparent, but if the fluid is notably dirty, it should be replaced.

Why do we replace/service:
Similar to engine oil, differential gear oil breaks down over time. It is under high stress and shear loads. As it breaks down, it allows more contact between the metal gears inside the differential. This leads to small metal particles to wear and will wear the gears more and more as time goes on.

What happens if we don’t service:
If services are not kept up with, differentials will wear prematurely. This leads to excess gear noise and will eventually lead to catastrophic failure.

General Recommendations:
Although some manufacturers do not suggest replacement ever, a differential fluid replacement may be cheap insurance to protect a somewhat pricey part. Follow your Lexus manufacturers recommendations for fluid weight and pay attention – some require additives such as for limited slip differentials, while others may require synthetic gear oil.

Pumped through the transmission and torque converter – responsible for heat dissipation, lubrication and protection

Service Interval: 15k-100k
Manufacturers vary greatly in service recommendations. Some suggest a drain and fill (only replacing 3 or so of the 9-12 quarts in the system), some a drain and fill with filter replacement, and some a full transmission fluid exchange. On vehicles that have a dipstick, the fluid should be relatively bright red in color and not have a burnt smell. If it is very dark or smells burnt, proceed with caution as noted below.

Why do we replace/service:
Like engine oil, transmission fluid breaks down over time, as well as loses its ability to keep the transmission internals clean. It is under extreme heat and pressure.

What happens if we don’t service:
The older the fluid, and the hotter it gets, the less it can do its job of lubricating and cooling your transmission. If your filter is dirty as well, it exponentially increases the problem, by restricting fluid flow, which can overheat your transmission. Essentially, this is just as important of a service as changing the oil and over the life of a car, actually costs less to do than an engine oil change, as the service intervals are much farther between.

General Recommendations:
Keep up with Lexus transmission services. Vehicles that suggest complete fluid changes are more important that this takes place on a regular service interval. If you are not sure when the last time your transmission was serviced, and you have it flushed, you may increase your risk of transmission failure. The main problem behind this is that when a dirty transmission is flushed, the detergents in the new fluid may dislodge contaminants leading to stuck solenoids and even more worn clutches. By doing drain and refills every oil change for 3-5 oil changes, you can turn your fluid back to a healthy cherry red color, and gradually remove the contaminants if the complete fluid replacements have not been done regularly.