Porsche 928, Frequently Asked Questions

Buying

What’s the best 928 variant for a first-time buyer?

The S4 automatic. It’s the most accessible 928: the 5.0-litre engine has enough power to feel properly fast (320 hp, 0-100 in 5.9 seconds), the automatic transmission is smooth and reliable, and the S4 generation benefited from a decade of refinement over the original car. The S4 is also the most plentiful variant on the used market, which means better selection, more competitive pricing, and wider parts availability. Most importantly, the S4 has been around long enough that the specialist community knows every weakness and every fix. It’s a solved car.

If you’re mechanically confident and want something more engaging, a manual S4 or GT is the step up. But for your first 928, an S4 auto with documented history is the smart play.

How important is timing belt history?

It is the most important single factor when buying any DOHC 928 (that’s the S, S4, GT, and GTS, basically everything from 1980 onwards). The 928’s V8 is an interference engine. If the timing belt breaks, the valves hit the pistons and the engine is destroyed. Not damaged, destroyed. A full engine rebuild starts at $15,000 AUD and can easily exceed $25,000.

The timing belt must be replaced every 4-5 years or 60,000 km, whichever comes first. The replacement must include the belt, all tensioner and idler rollers, and the water pump. You need documented proof: receipts from a reputable workshop showing the correct parts were used. A seller who says “I think it was done a few years ago” is a seller whose car needs a $3,000-5,000 timing belt service before you drive it.

If there’s no documentation, assume it’s overdue and price your offer accordingly.

Manual or automatic?

This depends entirely on what you want from the car. The automatic 928 is a superb grand tourer. It’s relaxed, refined, and makes the most of the V8’s torque for effortless cruising. The S4 and GTS automatics are well-matched to the car’s character, and most 928s left the factory with an automatic.

The manual transforms the experience. The 5-speed manual makes the 928 feel more like a sports car and less like a luxury cruiser. It’s more engaging, more involving, and gives you more control over the engine’s power delivery. The downside is that manual 928s are significantly rarer (perhaps 15-20% of production), significantly more expensive (30-50% premium over an equivalent auto), and the clutch replacement is a $4,000-7,000 job because of the torque tube layout.

For a daily driver or relaxed tourer, the automatic is the right answer. For a weekend driver or an enthusiast who wants maximum involvement, the manual is worth the premium.

What makes the GTS so special?

The GTS is the ultimate 928. The 5.4-litre V8 produces 350 hp and 369 lb-ft of torque, the engine is responsive and rewards hard driving in a way the earlier, smaller-displacement units don’t quite match. The wider rear track (30mm wider than the S4) improves stability and gives the car a more aggressive, muscular stance. The interior is the best-appointed of any 928. The suspension is revised and tuned for a sharper response.

But the GTS is also special because of its rarity. Only approximately 2,831 were built over four model years. The manual GTS is rarer still. This is the 928 that collectors want, and values reflect that. A clean manual GTS is a six-figure car in 2026 and the trajectory is upward.

How does the 928 compare to a 911 of the same era?

They’re fundamentally different cars. The 911 is a sports car: light, agile, visceral, with the air-cooled flat-six singing behind you. The 928 is a grand tourer: smooth, powerful, comfortable, with the V8 burbling ahead of you. The 911 is better on a twisty back road. The 928 is better on a 500 km highway blast. The 911 demands attention and rewards skill. The 928 is more forgiving and more relaxing.

Neither is objectively better, they’re designed for different purposes. Many enthusiasts eventually own both. If you’re choosing one, ask yourself: do you want excitement or refinement? Weekend blasts or long-distance cruising? The answer will tell you which car is right.

Are parts readily available?

Yes, better than you might expect. Porsche Classic maintains stock of many 928 parts, and the aftermarket has matured significantly. Engine internals, gaskets, timing belt kits, suspension components, and brake parts are well served. Body panels are available but expensive. Electrical components (switches, relays, modules) are the hardest to source, particularly for the pre-S4 cars.

The 928 community is strong and well-organised. Online forums, Facebook groups, and specialist suppliers like 928 International, Porsche Classic, and various independent specialists carry comprehensive inventories. In Australia, there are several Porsche independents with specific 928 experience, and the Porsche Club of Australia chapters can connect you with specialists in your state.

Driving and Ownership

Can I daily drive a 928?

Yes, many owners do. The 928 was designed as a daily driver, it was Porsche’s luxury GT, intended for comfortable long-distance commuting. It has air conditioning, power everything, a comfortable ride, excellent visibility, and a boot large enough for a week’s luggage (especially with the rear hatch).

The practical considerations are fuel consumption (14-18 L/100km in mixed driving, on 98 RON premium), the car’s age (even the newest GTS is over 30 years old, and things wear out), and the reality that parking a classic Porsche in public car parks invites door dings and unwanted attention.

Many 928 owners use the car as a weekend driver and occasional commuter rather than a true daily. The car is best enjoyed on open roads where the V8’s effortless torque and the chassis’s long-distance comfort can shine.

What fuel does the 928 need?

98 RON premium unleaded. The DOHC V8 (S, S4, GT, GTS) has a compression ratio of 10.0:1 or higher and requires high-octane fuel to avoid detonation. The earlier SOHC engine (base 928) can run on 95 RON but performs better on 98. Never run a 928 on standard 91 RON unleaded, you risk engine damage from detonation.

The 86-litre fuel tank means a fill-up at current prices is around $200 AUD. Budget accordingly.

What oil should I use?

A quality fully synthetic 5W-40 or 10W-40 oil meeting Porsche’s specifications. Mobil 1 0W-40, Castrol Edge 5W-40, and Penrite HPR 5 10W-40 are all popular choices among Australian 928 owners. The engine holds approximately 7.5 litres with filter change (varies slightly by model).

Oil changes should be performed every 10,000 km or annually, whichever comes first. Some 928 specialists recommend 7,500 km intervals for the later DOHC engines, particularly if the car sees hard driving. Always use a quality oil filter, the Mahle or Mann OEM-equivalent filters are the standard choice.

How often should the 928 be serviced?

Minor service (oil, filter, inspection): Every 10,000 km or annually.

Major service (all fluids, filters, comprehensive inspection): Every 30,000 km or every 3 years.

Timing belt service (belt, rollers, water pump): Every 60,000 km or every 4-5 years, whichever comes first. This is the big one, do not defer it.

Brake fluid: Every 2 years (hygroscopic, absorbs moisture).

Coolant: Every 3-4 years or as indicated by test strip.

Transmission fluid (auto): Every 60,000 km. Many owners do it more frequently at 40,000 km intervals.

Transaxle oil (manual): Every 60,000 km with a quality GL-4 or GL-5 gear oil.

Is the 928 expensive to insure?

Agreed-value classic car insurance is available from most specialist insurers and is reasonably priced for the coverage. Expect $1,000-2,500 AUD per year depending on the agreed value, your age, driving history, and usage pattern. The GTS will be more expensive than an S4 due to its higher agreed value.

Standard comprehensive insurance through mainstream insurers is generally not recommended because they’ll undervalue the car and pay out market value rather than replacement cost. Always insure on an agreed value basis through a specialist classic car insurer like Shannons, RACV Classic, or Hagerty.

What’s the 928 like in Australian conditions?

Very well suited. The 928’s comfortable ride, effective air conditioning, and long-distance touring ability make it an excellent car for Australian conditions. The V8 engine copes well with heat (it’s water-cooled and well-designed for thermal management, unlike some European cars of the era). The Weissach rear axle provides excellent stability on long, fast highways.

The main concern is the sun. Dashboard cracking from UV exposure is a serious issue, always use a windscreen sun shade when parked. The paint, particularly on dark colours, suffers from prolonged sun exposure. Covered parking or a garage is strongly recommended.

Maintenance

Why is the timing belt service so expensive?

The cost is almost entirely labour. The 928’s V8 has four camshafts driven by a single timing belt with multiple tensioner and idler rollers. Accessing the belt requires removing the front of the engine, including the cooling system components, and the job takes 8-12 hours for an experienced specialist. The parts (belt, rollers, water pump, seals) are $600-1,000. The labour is the rest.

It’s expensive, but it’s non-negotiable. An engine rebuild after a belt failure costs five to ten times more than the preventive belt service.

What are the most common modifications?

The 928 community tends towards reliability and performance modifications rather than cosmetic changes:

• Silicone vacuum hose replacement: Replacing every deteriorated rubber vacuum hose with silicone. This is almost a standard restoration item.
• Stainless steel coolant pipes: Replacing the corrosion-prone underbody coolant pipes with stainless steel.
• LH module relocation: Moving the engine management ECU from the hot engine bay to a cooler location.
• Sport exhaust: Aftermarket exhaust systems improve flow and sound. The 928 V8 sounds magnificent with a freer exhaust.
• Suspension refresh: Bilstein or Koni dampers with polyurethane bushings throughout.
• Larger brake rotors: Some owners fit larger rotors from the later models to earlier cars.

Avoid heavily modified 928s unless you understand exactly what’s been done. Many modifications from the 1990s and 2000s were poorly executed.

Can I work on the 928 myself?

The 928 is more DIY-friendly than its complexity might suggest, but it rewards preparation and patience. The engine bay is spacious by Porsche standards. Many routine tasks, oil changes, air filter replacement, spark plugs, brake pads, vacuum hose replacement, are within the reach of a competent home mechanic with a good set of tools.

The factory workshop manual is essential. Porsche’s original workshop documentation is thorough and well-illustrated. Digital copies are available from the 928 community. The Rennlist 928 forum is an invaluable resource, virtually every question you could ask has been answered there with detailed instructions and photos.

The timing belt service is the one job that most owners farm out to a specialist, the consequences of getting it wrong are too severe. Similarly, any work involving the torque tube (clutch, rear main seal, centre bearing) is best left to someone with a hoist and 928 experience.

Technical

What is the Weissach rear axle?

The Weissach axle is one of the 928’s most innovative features. Named after Porsche’s research and development facility, it’s a rear suspension design that provides passive rear-steer for improved high-speed stability.

The system works through carefully designed compliance in the rear suspension bushings. Under braking, the forces acting on the rear suspension cause the rear wheels to toe in slightly (point inward). This has a stabilising effect, counteracting the tendency for the rear of the car to step out under hard braking. The effect is subtle but significant, it makes the 928 feel planted and secure during hard braking from high speed, a critical attribute for a car designed for autobahn cruising.

The downside is that the Weissach axle bushings wear, and worn bushings produce vague handling and a nervous rear end, the opposite of the intended effect. Bushing replacement is a standard maintenance item on any 928 with significant mileage.

What is the torque tube?

The torque tube is a rigid aluminium tube that connects the front-mounted engine to the rear-mounted transaxle (gearbox and differential). The propeller shaft (driveshaft) runs inside the tube, supported by a centre bearing. The torque tube is a structural member, it transmits the engine’s torque to the transaxle and contributes to the chassis’s overall rigidity.

The torque tube layout gives the 928 its near-perfect 50:50 weight distribution. The engine sits at the front, the heavy gearbox and differential sit at the rear, and the torque tube ties them together. The practical consequence is that any work on the clutch, rear main seal, or centre bearing requires separating the engine from the transaxle by removing the torque tube, a major and expensive job.

Is the 928’s V8 related to any other Porsche engine?

No. The M28 V8 was designed from scratch for the 928 and was never used in any other Porsche model. It shares no significant components with the 911’s flat-six, the 944’s inline-four, or any other Porsche engine. It is an all-aluminium, 90-degree V8 that evolved from 4.5 litres (SOHC) to 5.4 litres (DOHC) over the 928’s production life.

The M28 is widely regarded as one of the finest V8 engines of its era, smooth, powerful, durable, and characterful. Its all-aluminium construction was ahead of its time; most V8s of the late 1970s still used iron blocks.

What gearboxes were fitted to the 928?

Automatic options:

• 3-speed Mercedes-Benz automatic (early 928 and 928 S)
• 4-speed Mercedes-Benz automatic (S4, GT, and GTS)

Both are durable and well-suited to the car’s character. The 4-speed is a significant improvement over the 3-speed.

Manual options:

• 5-speed manual, Porsche-designed, rear-mounted in the transaxle housing

The manual was a factory option on all 928 variants but was ordered on a minority of cars (approximately 15-20% of production, varying by market and model year). Manual cars are significantly more valuable today.

How many 928s were built?

Approximately 61,056 across all variants over 18 years of production (1977-1995). For comparison, Porsche built roughly 250,000 911s during the same period. The 928 was always a low-volume car, and survivor numbers are lower still because many were scrapped when maintenance costs exceeded their depressed values in the 1990s and 2000s.

The GTS is the rarest production variant at approximately 2,831 units. The GT is also rare at approximately 2,897 units. The base 928 and 928 S are the most common, but finding a well-maintained example of any variant is increasingly challenging.

Value and Community

Are 928 values rising?

Yes, significantly, particularly for the GTS and GT. The 928 spent decades as an undervalued car, dismissed by 911-centric Porsche enthusiasts and punished by high maintenance costs that scared off casual buyers. That has changed. The current generation of enthusiasts recognises the 928 for what it is: a brilliant, beautifully engineered GT that happens to have a Porsche badge.

The GTS manual has seen the most dramatic appreciation, with clean examples now regularly exceeding $150,000 AUD. The S4 and GT have also risen steadily. Even rough, project-grade 928s have increased in value as the supply of good cars dwindles.

The 928 is following the same trajectory that the 911 followed 15-20 years ago: once-cheap cars becoming recognised classics with values rising accordingly.

Is there an active 928 community in Australia?

Yes. The Porsche Club of Australia chapters (in each state) welcome 928 owners, and there are dedicated 928 groups within the broader Porsche community. Internationally, the Rennlist 928 forum is the single best online resource, with decades of accumulated technical knowledge, buying guides, and owner experiences.

In Australia specifically, there are several independent Porsche workshops with strong 928 expertise, particularly in Sydney, Melbourne, and Brisbane. The community is smaller than the 911 community but genuinely passionate and helpful. New 928 owners are welcomed with open arms, these people want more 928s on the road.