16 hours ago, DD_Arthur said:

Hmmm...nothing that magical about synthetic oils.

 

I used to work a lot on cars many years ago but I'm certainly not an expert these days. Annoyingly I'd have to refer to Google. Sorry about that. 😁

"Yes, synthetic oils allow for significantly longer oil change intervals than conventional oils, often extending from 7,500-10,000 miles or more (even up to 15,000-25,000 miles for some advanced types) compared to the traditional 3,000-5,000 miles for conventional, due to their superior stability, resistance to breakdown at high temperatures, and uniform molecular structure. However, always check your vehicle's owner's manual for specific manufacturer recommendations, as driving conditions, vehicle age, and driving habits heavily influence the best interval. 

 

Why synthetic oil lasts longer

• Better thermal stability: Synthetic oil doesn't thin out as quickly in extreme engine heat, providing better lubrication and protection.
• Molecular uniformity: Its consistent molecular structure resists evaporation and degradation better than conventional oil.
• Cleaner performance: It stays cleaner for longer, reducing deposits and allowing for extended intervals. "

 

 

Edited December 28, 2025Dec 28 by martin-w

16 hours ago, Reader said:

The idea of a 1 litre petrol engine with a massive turbo might look good on paper, but they have been
beset by other problems,

 

They aren't massive turbos, unless its some kind of very high performance car. Can't say ive ever had issues with turbos on my past cars, to be honest.

17 hours ago, Reader said:

This is absolutely not the best.
In many cases, ludicrously long oil change intervals of up to 20,000 miles have proved to
drastically shorten engine life.

Similar supposed fuel saving devices such as Stop Start technology have been shown to drastically shorten
the life of turochargers, that continue to spin in some circumstances at high rpm after their oil supply has
been cut off by the stop start killing the engine.

 

Do you have a link to anything suggesting manufacturers service intervals are wrong? To be honest, I'm not a fan of stop start technology, either. 

As someone who worked in the industry and attended a course on oils and lubricants, synthetic oil is made from petroleum and even electric vehicles need lubricants.

4 hours ago, martin-w said:

Regarding EV's, Tesla batteries are warranted between 100,000 miles and 150,000 miles, dependent on model, I understand. Not sure about motors. 

I believe the battery warranty is 8 years *or* 150,000 miles, likely whichever comes first.  After about 8 years the battery will have degraded to about 70% of its original capacity, and perhaps more depending on the type of driving, how many charging cycles, etc.

A Tesla EV battery replacement costs between $13,000 and $20,000.  A drive motor replacement costs $5,000 to $10,000.

Dave

 

1 hour ago, dave2013 said:

I believe the battery warranty is 8 years *or* 150,000 miles, likely whichever comes first.  After about 8 years the battery will have degraded to about 70% of its original capacity, and perhaps more depending on the type of driving, how many charging cycles, etc.

A Tesla EV battery replacement costs between $13,000 and $20,000.  A drive motor replacement costs $5,000 to $10,000.

Dave

 

 

70% is the warranty degradation, at least 70%. In reality it's as below...

 

 

Quote

 

Tesla batteries typically degrade around 10-20% over 8 years, with most loss happening early (5-10% in first few years) and slowing to about 1-2% annually, meaning most models retain above the 70% capacity guaranteed by Tesla's warranty, often staying closer to 80-90% even after significant mileage. Real-world data suggests average yearly loss is closer to 1-2%, but factors like charging habits and climate affect this. 

 

In Summary: While warranty ensures 70% capacity, most owners find their batteries remain well above that, often in the 80-90% range after 8 years, according to real-world data and owner reports. 

 

 

 

 

 

Quote

 

Tesla batteries are built to last 300,000 to 500,000 miles (or about 15-20 years), significantly longer than their standard 8-year warranty, which guarantees at least 70% capacity retention, though degradation starts with a quicker 5-10% loss in the first couple of years before slowing to about 1% annually, with usage, charging habits (like avoiding 100% charges), and temperature affecting overall longevity. 

 

Expected Lifespan & Degradation

• General Range: 300,000 to 500,000 miles, often outlasting the car itself.
• Initial Drop: Expect a 5-10% capacity loss in the first 2 years.
• Slower Decline: After the initial period, degradation slows to roughly 1% per year. 

 

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Edited December 28, 2025Dec 28 by martin-w