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The dangers of do-it-yourself maintenance

Car manufacturers have been steadily steering customers away from do-it-yourself servicing – with the exception maintaining the vehicle's fluid levels.

Increasingly, consumers popping the hood to check the dipstick have to be prepared for the fact it may not be there. It's incomprehensible why many manufacturers expect customers to top up their engine oil between oil changes, but can't provide a dipstick to make the task easier. Failing to maintain the proper level – whether too low or too high – can lead to undesirable warranty predicaments.

A customer of ours recently experienced just such heartbreak. His BMW 335i, sans dipstick, alerted him to add a "litre of oil immediately." Having recently purchased the car second-hand, he was unprepared to deal with this style of electronic system and lost track of the oil level. He added multiple litres of oil over a short period of time and the warning indicator reversed as he drove, indicating it was now overfilled.

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However, he kept going, not realizing the severity of his mistake. When the car was finally towed to us, we were told it had smoked badly before dying. It didn't take long to realize that the car had an overfill condition and a hydrolock had occurred, a situation where a non-compressible fluid enters a part of the engine that is normally occupied by a compressible gas.

The engine was permanently damaged by the 18 litres of oil that occupied it, more than double its recommended capacity. This is an extreme "what were they thinking" moment, but it happens more often than it should – presenting the question of who will pay for the repairs. The lack of a dipstick may be a questionable engineering manoeuvre, but it's clear who's at fault. The warranty company is well within its right to decline paying for repairs.

Performance enthusiasts also have to be wary of the potential to void their factory warranty. Turbocharged vehicles are ripe for "tuning," which is non-sanctioned reprogramming of the onboard computer. The Ford 6.0-litre power stroke engine available in its mid-2000s pickups were one of the first turbocharged diesels to be eagerly tuned by owners seeking more power.

This software modification allowed the engine's turbocharger to provide far more boost than it did in stock configuration, and many of these trucks experienced premature head-gasket failure because of the increased internal engine pressure.

Ford initially denied many warranty claims but eventually concluded the engine had a head-bolt defect, and the performance modification was just shortening the failure interval. Most manufacturers now scrutinize a vehicle's software before approving warranty engine repairs on turbocharged models.

Technological advancements have resulted in a steady decline of do-it-yourself car maintenance, but there are still those that enjoy car-tinker time. However, it's easy to get in over your head, given new cars' complexity and the speciality tools required.

Home mechanics need to keep accurate receipts and records because the dealer will want proof of proper interval fluid changes if it is going to approve a major repair during the vehicle's warranty period.

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