What is the real danger in extending the time specified for servicing a car?

Tuesday January 15 2019

The older the engine, the more susceptible it is to oil-based failures. PHOTO| FOTOSEARCH


Good Morning JM,

Thanks for the candid information you extend to us on motoring subjects. I have several questions for you. What happens to a vehicle’s performance/engine when the car is subjected to a late or extended oil change? Does this affect fuel consumption for the period that is subjected to delayed oil change?

And finally, for the oil that guarantees 10,000 kilometres and 5,000 kilometres, what would be your advice/preference to motorists and the caution to take on these. Justus Maranga


To respond to your first question, it depends on how far beyond the stipulation your extension goes; and the prevailing mechanical state of your car. If the car is in good working order, you can harmlessly get away with a few extra thousand kilometres but try not to make it a habit.

"A few extra thousand kilometres" is also very relative: If you overshoot your service interval by 20,000km, then you only have yourself to blame when your engine digests itself or tries to commit gunk-based seppuku. I repeat: try and stick to the programme. It is for your own good.


It need not be said that older, higher mileage engines are more intolerant of unfaithfulness to the servicing timetable. This is especially pertinent to vehicles operating in extreme conditions; the sort where people working there have to be paid a hardship allowance.

If you operate in dusty conditions, ford water often or even drive in normal places but the engine is always under a lot of load, yea, you should stick to the schedule or pay the price.

To your second question, I would have thought not, but this was made very apparent and very clear during the final two months of 2018.

I mentioned earlier that a W210 Mercedes-Benz E Klasse joined the garage in 2.3 litre, M111-powered, 4-cylinder form. Now, shortly after acquiring it, I subjected it to an extended road trip up the walls of the Rift Valley and I must say the fuel consumption was not impressive at all.

The seller (my lawyer, ha!) sternly reminded me that he had specifically said to service the car as the first order of business. The car was duly serviced and subjected to yet another extended road trip, this time past the walls of the Rift Valley and lo and behold!

Same driver, same driving style, same roads, broadly similar conditions (if anything, the conditions of the second trip were more arduous than the first) but this time, the car just wouldn't drink. Hmm. Who would have thought?

I know theories about engine compression come up when discussing oil but the Benz doesn't have that many kilometres under its belt and I did not think the difference would be that extreme.

I have pushed both El Turbo and the Mazda lago beyond recommended service intervals (but not by far) with no discernible flagging in performance or economy, but in the Benz, it really was shocking.

(Full disclosure: I did not use my mathematical method of distance divided by litres to work out the economy figures, but I used something slightly similar: full tank at Nairobi and distance driven to illumination of the warning light, and the difference before and after servicing that Merc was stark. Very interesting.)

Finally, the advice/preference/caution is fairly obvious but it may bear repeating just to be sure: stick to recommended service intervals, don't create your own.

RTFM: Read The [expletive] Manual and find out the kind of oil the manufacturer engineered your motor for. Don't do the equivalent of smearing Vaseline on a Formula 1 crankshaft and expect that engine to see tomorrow. Also, the older the engine, the more susceptible it is to oil-based failures, so be very keen, more so with the warning lights.

(Not a very fun fact: In a Subaru, by the time the oil warning light comes on it's too late. Budget for a replacement engine).

A personal perspective is a deep-seated mistrust in oils that claim to have life up to 10,000km. Yes, with a high strung 2.0 litre turbocharged engine from an Impreza WRX nestled in El Turbo's bonnet bay, I think not.

The maximum I will gamble with is maybe 7,500 (if the tin says 10k), otherwise I stick to 5k.
Now that we mentioned Mercs earlier, there are those that rather than do distance-based service protocols, the engine self-diagnoses and like a true hypochondriac, decides for itself when it needs servicing.

With the right oil and the right conditions, one can eke as many as 25,000km between oil changes. So you really do need to RTFM to have a painless lubrication experience.


Fuelling a car. PHOTO| FILE

Here is how to know if your car is really consuming more fuel than it should be

Hello JM,

I am an avid reader of your write-ups on motoring. I have a 2011 Toyota Fielder which is a four-wheel-drive full time. I bought it early this year directly from Japan. In my assessment, its fuel consumption is high, since I use fuel of between Sh1,000 to Sh1,500 daily to and from work, for a distance of about 60 to 65 kilometers. I have consulted some mechanics and I have been advised that the solution is to do away with the four-wheel and modify it to two-wheel. Is this possible and would this interfere with the mechanical system of the vehicle or adversely affect its performance on the road? Please advise, Umaje

Dear Umaje,

There are a few things you are doing wrong, the first being quantifying fuel in terms of variables: what you paid for; rather than constants: volume (litres) or mass (kilos). Between capitalistic, profiteering energy companies and the ERC, the fuel price today is not usually the same as it will be tomorrow, so what exactly is Sh1,000?

It could be eight litres if the price is Sh125 per litre, it could be 10 litres if the price is Sh100 per litre and anything in between or even beyond.

Secondly, you are very vague. “Between Sh1000 and Sh1,500 daily” is how much exactly? Sh1,250? “Between 60 and 65km” is how far exactly? 63? How do we even calculate your fuel consumption to know whether or not it is off the scale based on such ambiguity?

So, leave the AWD/4WD system alone first. Don’t touch it because I seriously doubt it has wronged you in any way. This is how to calculate your fuel consumption:

1. Fill your tank to the brim (okay, to the fuel cut-off point). Take note of your odometer reading at that point.

2. Resume your normal driving schedule. Try not to change anything or do anything out of the ordinary. Drive as you usually do. Do this over several hundred kilometres and/or at least there is a noticeable drop in fuel levels in the tank, preferably when the needle/scale/gauge gets to a quarter or just below a quarter.

3. Refill the tank (to the brim, like the first time). Take note of the amount of fuel that goes into the tank this second time (in litres, not Kenya shillings). Take note of the new odometer reading.

4. Your fuel consumption is: distance covered between fill-ups (second odometer reading minus first odometer reading) divided by the amount of fuel (in litres, not Kenya shillings) dispensed in the second fill-up. Simple.

Come back with this number then we can compare notes and decide if the vehicle is thirstier than it should be and if so, what can be done to slake this thirst somewhat, without removing driveshafts.

Would you advise me to replace my car’s rear drums with disks?

Hello JM,

My wife’s Toyota Premio has some unpredictable braking especially during the rains. My mechanic says that the pads and other braking components are okay but if I need responsive braking, I need to replace the rear drums with disks. How true is this? Is my mechanic trying to open my wallet riding on the sentimental value of my better half? You see, I see Hondas, Mazdas, Subarus and even cheap Nissans of roughly the same price range and YOM equipped with rear disks. Is Toyota deliberately cutting costs at the expense of safety? From a point of ignorance, I only see drum brakes on trucks, prime movers, buses etc, which generally require robust braking, so who is suffering fools here? M.N

Hello M.N,

I may need deeper explanation as to what “unpredictable” braking is. You also mention “responsive” braking. Most braking problems are caused by wear and tear of sundry components (pads, shoes, drums, discs, master cylinder, slave cylinder and many more). The solutions, therefore, involve replacing affected parts and not re-engineering the entire braking system of the car.

Developing a braking system is expensive, especially calibrating the ABS. I don’t mean a lot of money like hundreds of thousands of shillings, I mean a lot of money like entire car companies such as TVR and Noble selling vehicles without ABS because they lack enough funds to run a development programme for it. You get the picture.

We are talking millions of dollars here. That is essentially what you’ll be doing when replacing the rear drums with discs. You’ll be re-engineering the braking system of your car.

I once asked The Paji (RIP) to perform a similar operation on the Mazda lago and he took me through the task list — which involved replacing the entire rear subframe, among other things — after which I decided perhaps drums are not so bad after all.

These are not the only downsides. Your own safety is at stake because brake balance will be thrown off, and with discs at the back (without the added benefit of a bottomless piggy bank and highly motivated boffins of anchorage to fine-tune the set-up), the brake bias shifts aft and the increased rear braking force means you will wipe out and crash heavily the day you drop anchor; more so given that you seem to brake a bit more aggressively than you have a right to if you are complaining about drum brakes on normal road use.

So, that being said:

1. The mechanic seems more to be experimenting than even gunning after your money. There has to be another cause to the “unpredictable” braking which is not as “responsive” as you like. It may be the system needs an overhaul (and not further development like your mech is trying to do) or perhaps your expectations are unrealistic for a vehicle equipped with drum brakes, but again I ask: Just what kind of braking exactly do you do for you to consider a replacement of the rear axle?

2. Yes, drum brakes are used to keep vehicle costs low. I’m sure those Nissans, Hondas and Subarus have drum-fitted variants in their line-ups, just as I’m sure the (more expensive) Toyotas have high-spec versions with discs all round.
Drum brakes are not exactly unsafe unless used in extremities such as on a racetrack, but you may be on to something here: as motor vehicle safety systems go, autonomous or automatic emergency braking is soon becoming compulsory on new cars and with it will come a demand for shortened braking distances of which drums are not capable. One day it will be discs all round for everybody.

3. Look around harder, you’ll see disc brakes on trucks. They drive among us. They are more likely to appear on European marques than Japanese ones. We even have a Mombasa-bound Scania bus boasting of disc brakes on all three axles.

The same costing thing applies here: commercial vehicles have long used drum brakes to keep prices low and thus allow them a competitive advantage in the market; plus, most of them come with auxiliary braking systems such as engine brakes, Jake brakes, exhaust brakes and retarders, meaning they don’t rely on wheel brakes as much as lighter and smaller vehicles do.


Which is the best (4by4) automatic pickup with high fuel efficiency? PHOTO| FILE

Help me settle on the best 4X4 automatic pickup

Hallo JM,

Which is the best (4by4) automatic pickup with high fuel efficiency? I am interested in the Hilux, D-Max, Navara, Mitsubishi L200, Ford Ranger and 2017 Chevrolet Colorado. Titus

Hello Titus,

I won’t answer your question now because this will call for a massive comparison test that should even be televised. I have experienced and can have access to the Hilux and the D-Max. I’m 50:50 on the Navara and L200 — confirmation pending. Ford has not yet acknowledged the existence of this column.

The Chevrolet Colorado is American, but should be related to the Holden Colorado, which is just a shiny D-Max anyway.

So, one giant comparison test coming up. It may or may not involve all the listed participants — we could throw in an Amarok for good measure and maybe a Chinese trucklet just to shake things up a little — but I will definitely try to capture it on film. Keep an eye peeled.

Is there an engine difference between Toyota GT86 and Subaru BRZ2013

Hallo JM,

I am a sports car enthusiast who has been troubled for a while now, trying to find a replacement for my ageing Celica. I had recently settled on a 2013 Subaru BRZ. Then I browsed through a Toyota GT that looks exactly like the BRZ, both inside and outside, except the GT has less engine capacity. Now I am torn between the two. Help Phillip

Dear Phillip,

The GT (GT86 in full) doesn’t have less engine capacity. That car and the BRZ are the exact same thing, right down to engine capacity (2.0 litres, horizontally opposed, good for about 197hp).

There is no hyperbole here when saying the Toyota GT86 and Subaru BRZ (and for a short time, the Scion FR-S) are the same. It actually is the exact same car; the buyer’s choice boiling down to what logo they prefer to look at when approaching the vehicle grille-first.

So between Toyota and Subaru, which brand name appeals to you more?