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If you’ve ever turned the key on a cold morning and heard nothing but that depressing “click… click…”, you know the instant panic of a failing starter motor or alternator. Once you’ve confirmed the part is dead, the next headache begins:

“Do I buy the genuine dealer part… or save money with an aftermarket one?”

At Starter Motors & Alternators, we specialize exclusively in the supply of these units. We know exactly what sits inside these boxes, and the truth is, the "right" answer depends on understanding what you're actually paying for.

This guide breaks down the debate so you can get your vehicle back on the road without overpaying or compromising on reliability.

 

What Are OEM Parts? (The Dealer Standard)

OEM stands for Original Equipment Manufacturer. These are the parts fitted to your car on the assembly line.

Pros:

• Guaranteed Fit: No adjusting or "making it work."
• Exact Spec: Built to handle your car’s specific electrical load (heated seats, stop/start tech, etc.).
• Warranty Friendly: Perfect for newer vehicles still under manufacturer warranty.

Cons:

• The "Brand Tax": You are often paying for the car manufacturer’s logo on the box.
• High Price: Usually the most expensive option on the market.

 

The "OE Supplier" Secret: The Smart Way to Buy

Here is a secret the big car brands don't want you to know: Car companies rarely make their own starters or alternators.

They outsource them to specialist giants like Bosch, Valeo, Denso, and Mitsubishi Electric. When you buy a "Genuine BMW" alternator, you are often just buying a Valeo unit in a BMW box.

 

The Starter Motors & Alternators UK Approach

We stock these same OE Supplier brands. By buying the Bosch or Denso unit directly from us rather than a main dealer, you get:

1. The identical part found in the car from the factory.
2. The same performance and longevity.
3. A significantly lower price because you aren't paying the dealer markup.

 

What About Aftermarket Parts?

Aftermarket parts are made by third-party companies. In the world of rotating electrics, these fall into two categories:

1. High-Quality Brand Aftermarket

Reputable brands often "reverse engineer" the original part. Sometimes, they even improve it by using heavier-duty brushes or better bearings to fix known flaws in the original design. These offer a fantastic balance of price and performance.

2. The "White Box" Danger (Cheap Internet Parts)

You’ve seen them, suspiciously cheap units on marketplaces with no brand name. We strongly advise against these for starters and alternators.

• The Risk: Low-grade copper windings and weak solenoids lead to overheating, battery drain, or total failure within months.
• The Cost: A cheap starter that fails in six months ends up costing you double in labour and downtime.

 

Comparison at a Glance

Feature	OEM (Main Dealer)	OE Supplier (The Smart Choice)	Quality Aftermarket
Price	Very High	Competitive	Affordable
Quality	Excellent	Excellent (Identical)	Good / Improved
Reliability	10/10	10/10	8/10
Fitment	Perfect	Perfect	Perfect
Best For	New cars under warranty	Most drivers & professionals	Older cars / Value seekers

Frequently Asked Questions

Does using an aftermarket part void my warranty?

No. Under Block Exemption Regulations, you can use "OE Quality" parts (like the ones we supply) without voiding your vehicle's manufacturer warranty, provided they are installed correctly.

Why not just repair my old one?

While some shops offer repairs, replacing the entire unit with a brand-new, warranted component from Starters-Alternators.co.uk is often the more reliable choice. It ensures every single internal component, from the voltage regulator to the bearings is fresh and ready for years of service.

 

Conclusion: Which should you choose?

For a component as critical as a starter motor or alternator, we always recommend sticking with OE Supplier brands (Bosch, Valeo, etc.) or High-Quality Brand Aftermarket units.

Saving £20 on a "no-name" part isn't worth the risk of being stranded on a rainy Tuesday morning.

Ready to find the right part?

Use our search bar tool at Starter Motors & Alternators UK to find the perfect match for your vehicle by cross reference or part number. If you're unsure which brand to go for, our expert team is just a message away!