Should I Buy a Ford Ranger Ute Despite the Oil Change Issue?


Attention DIY-ers: if you drain the oil on a Ranger or BT-50 for more than 10 minutes you might destroy your engine. Is servicing complexity out of control?


It’s always the stuff you don’t know you don’t know that could cost you thousands…

This report is motivated by a question from you.


“I’m in the market for a dual cab 4x4 Ford Ranger XLT. I like to do an engine oil and filter service myself between manufacturer-specified service intervals so my engine is always running clean.” - Evan


OK - I guess. Each of us … we like what we like. I like to think of myself as a kind of fishnet-wearing, modern-day Clint Eastwood, which is as ridiculous as doing OCD oil changes.

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Hypothetically, you cannot hurt an engine with more frequent oil changes than the service manual stipulates. But many highly qualified engineers sat down and figured out how often your engine really needs servicing, using actual testing. So I’d go with their recommendation. Because: brainiacs.

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DIY versus warranty

Here in Australia, if you do any servicing on your vehicle (unless you’re a qualified mechanic) you risk voiding the warranty. It’s that simple. You don’t have to use an authorised dealer, but you do have to use a qualified mechanic (according to the ACCC).

Manufacturers can require this as a condition for ongoing warranty compliance, and there’s nothing you can do about it. No clever argument will get you around it.

You also have to conform to the required service schedule and use parts that are fit for purpose - but they don't have to be genuine parts.

Also, in the fine print, for many vehicles, there’s a harsh operating conditions caveat, which usually advises an intermediate change for harsh conditions.

That’s fair, but what most people don’t get here is that ‘harsh conditions’ includes mainly short trips in cities, with lots of cold starts. Because driving like that really is hell on earth for engine oil.

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10-minute time limit

Evan went on:


“I discovered the variable pressure oil pump in the 3.2-litre Ranger and Mazda BT50 are unable to re-prime themselves and deliver oil pressure if they are left to drain for more than 10 minutes. Obviously this will cause catastrophic engine failure, so how do the dealers overcome this problem?

“Does this mean you can never let all the old oil drain out completely? Is there some way to prime the pump before starting the engine? I do not want to spend my money on a vehicle if I can't do basic service and oil change myself, especially if I am traveling and not near a dealer. Any technical advice on this issue would be greatly appreciated.” - Evan


It’s absolutely true that the Ford Ranger and Mazda BT-50 oil pump risks losing its prime if you drain the oil for more than 10 minutes. This is one of those Donald Rumsfeld-style ‘unknown unknowns’ - something you don’t know that you don’t know - because you think you know how to change the oil. And perhaps it never crosses your mind to investigate.

Servicing complexity & modern vehicles

Changing the battery

These are always the things that bite you on the arse. Just like changing the battery. If you disconnect the battery on a modern car, it can make the infotainment system think it’s been stolen - and generate a whole bunch of other ECU-initialisation kinds of issues.

Which is why people who change batteries for a living use small auxiliary batteries - often connected to the 12-volt outlet in the cabin - to power up the CAN bus while the main battery is disconnected for the changeover.

DPFs & oil dilution calibration

I guess it’s a similar thing with many modern diesels and oil changes. There’s an engine control ECU setting for oil dilution. Often you need to go in an reset that with a laptop after an oil change, so the engine can make the right set of decisions about regenerating the DPF.

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It’s complex - but the complexity is excusable, because it’s a tradeoff against delivering greater benefits thanks to the technology, which demands that complexity. There’s no valid argument against this - although there’s obviously a balance between those two things.

If you own a Bugatti Veyron, it’s, like, $20,000 to change the oil because, hey … you’re a rich tosser and they know.

Inside the 10-minute time limit

So why did Ford do this with the 3.2 in the Ranger and the BT-50? Because it seems superficially stupid, and many mechanics will tell you it is.

But really it’s not. They had their reasons. The benefit is that the oil pump varies the oil delivery in response to revs - in other words it's a variable-flow pump rather than fixed flow.

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This optimises the oil delivery across a range of operating revs and minimises the parasitic fuel consumption related to driving the oil pump. Maybe additional oil flow at high revs doesn't have to be bled off through a relief valve. I don’t know the specifics at that detailed level. But that’s why they did it.

But I do know that ancillaries - alternators, water pumps, oil pumps - they’re all essential components, but you can derive a direct fuel economy benefit by minimising their power consumption. Which is clearly the objective here.

Servicing professionals simply manage to get the new oil back in, within the 10-minute window.

Adequate drain time?

Here’s the bit where Evan and I disagree.

Modern oil is quite thin, so there’s no problem draining it, whipping the new filter on, and re-filling in under 10 minutes. There’s no practical benefit to the engine in letting the last 12 drops of old oil fall out over the next three hours (or something), which is what anally retentive DIY oil changers often do.

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This seemingly endless draining of the sump is, of course, nuts. Even if there’s 50 CCs of drainable old oil still in there, and there’s probably not - five minutes is a long time to sit there draining…

...but even if there is, 50 CCs diluted against five litres of new oil is only one per cent by volume, which is nothing.

And even those contaminated (probably not) 50 CCs of old oil … it’s probably 10 per cent contaminants and 90 per cent viable oil.

So that’s like one part per thousand of contaminants once the new oil goes in. Which is nothing. In the context of long-term reliable engine operation, it’s insignificant.


To me, this oil change time limit is absolutely not a reason not to buy a Ranger or a BT-50. It’s just a procedure that you need to follow if you own one. It has absolutely no negative consequences - just don’t get distracted, which is always good advice when you’re on the tools.

Evan’s implication that the oil change is in some way dodgy if performed in under 10 minutes is just not supported by facts - although I would drain the sump soon after shutdown, just because the contaminants are more likely to be evenly mixed through the oil, and it’s at its thinnest while it’s still hot.

The big warning here is: Use a mechanic, especially while the car is under warranty. He’s much more likely to know a bunch of the things you don’t know that you don’t know.

And don’t presume procedures you learned several decades ago still apply to modern cars today. Cars evolve - and therefore servicing does too.

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