S65B40 and S65B44: A Guide to the BMW M3 E90/E92/E93 Engine
Quick Summary
The S65 is a naturally aspirated V8 fitted to the BMW M3 E90/E92/E93 from 2007 through 2013. It’s a light engine at 240 kg, with an unlined aluminum block, a timing chain, and double VANOS. Its main weakness is the rod bearings, which need inspection every 19,000 miles. Maintained properly, the engine is good for 186,000 miles.
The Problem
You climb into your M3 and the engine idles rough. Or you notice the oil level dropping faster than it should. The S65 is a legendary motor, but it demands attention. Owners who ignore the maintenance schedule risk spun rod bearings and a destroyed engine. The repair bill is steep, and an unlined aluminum block is difficult to salvage.
Symptoms
- Rough idle
- Unusual noise from the front of the engine
- Fault codes for the camshaft sensors and throttle bodies
- Bluish smoke from the exhaust under hard throttle
- Loss of power and rising fuel consumption
- Oil consumption above 1 liter per 600 miles
Causes
Worn rod bearings — the most critical issue. Factory bearings rarely last past 50,000 miles. Beyond that, they can spin, damaging the crankshaft and connecting rods. Many owners replace them preventively at 31,000–37,000 miles.
Double VANOS problems — the cam phasers act up, developing play and throwing fault codes. The engine loses power.
Worn plastic gears in the drive for the eight throttle bodies — the gears crack and crumble, causing uneven running.
Rising oil consumption by 62,000 miles — most often worn valve stem seals or piston rings.
The Fix
10W-60 oil is mandatory. It protects the unlined aluminum block, which has no cast-iron liners. System capacity is 8.8 liters. Change it every 4,300–6,200 miles. Skimping on oil accelerates wear.
Bearing checks every 19,000 miles. Drop the oil pan and examine the bearings. Wear shows up as scoring and discoloration. Specialists recommend upgraded ACL rod bearings.
Check the throttle gears at the first sign of wear. Swapping in metal ones solves the problem for good.
98 RON fuel only. Detonation destroys the pistons and cylinder walls of the unlined aluminum block. Fill up at stations you trust.
| Specification | S65B40 | S65B44 |
|---|---|---|
| Displacement | 4.0 L | 4.4 L |
| Power | 420 hp | 450 hp |
| Torque | 295 lb-ft | 327 lb-ft |
Prevention and Used-Buyer Checklist
- Check the rod bearings — if the car has over 50,000 miles and there’s no paperwork showing a replacement, budget for the job
- Listen for double VANOS noise on a cold start and pull fault codes with a scanner
- Gauge oil consumption: bluish smoke under hard throttle is a red flag
- The engine number is located behind the alternator — verify it against the VIN
- Ask for the service history: regular 10W-60 oil changes and bearing replacements are a good sign
The Bottom Line
The S65 is one of BMW’s last naturally aspirated V8s, prized for its throttle response, linear power delivery, and sound. 186,000 miles is achievable with timely bearing replacements, 10W-60 oil, and 98 RON fuel. Tuning — a displacement increase to 4.4 liters, an exhaust and air filter swap, and a reflash — raises output to 450–480 hp without sacrificing reliability. Before you buy, check the bearings, the VANOS, and the service history.