Würth Engine Flush & Cleaner and Liqui Moly Engine Flush come from the same group. Würth owns Liqui Moly outright. Put the two safety data sheets side by side and the base is nearly the same: a C10-C13 hydrocarbon solvent at 70-90%, plus a ZDDP anti-wear additive. The gap is small. Both sheets list the same calcium detergent; Würth adds more base-oil fractions and a trace of methyl methacrylate.
Composition: Würth vs Liqui Moly (from the safety data sheets)
Here I put each brand’s standard flush next to the other: Würth Engine Flush & Cleaner 400 ml (SDS 2026) and Liqui Moly Engine Flush 2640. Every number below comes from Section 3 of the actual safety data sheets, not the label:
| Property (per SDS) | Würth Engine Flush & Cleaner | Liqui Moly Engine Flush 2640 |
|---|---|---|
| Solvent base | C10-C13 hydrocarbons (isoparaffins), 70-90% | C10-C13 hydrocarbons (isoparaffins), 70-90% |
| Anti-wear additive (ZDDP) | yes, 1-2.5% | yes, 1-2.5% |
| Detergent (calcium sulfonate) | yes, 1-2.5% | yes, 1-2.5% |
| Extra base-oil fractions | 5 (incl. white mineral oil), 1-10% each | 3, 0-5% each |
| Methyl methacrylate | yes, 0.1-1% | none |
| Main hazards (Section 2 classification) | Aspiration hazard (H304), skin sensitiser (H317), eye irritation (H319) | Aspiration hazard (H304), skin sensitiser (H317), eye irritation (H319) |
| Brand owner | Würth Group | Würth Group (Liqui Moly GmbH) |
Why are the formulas so alike? Because both brands belong to Würth
That overlap is no accident. Liqui Moly is 100% Würth Group, so the two flushes are built the same way: a mild, aliphatic (paraffinic) C10-C13 solvent base instead of harsh aromatics, plus a ZDDP additive that protects the sliding surfaces during the flush. Both sheets list the same base range, 70-90%, and the same ZDDP, CAS 68442-22-8, at the same concentration. In practice both clean moderately and go easy on the seals.
The real differences
Two differences actually show up in the sheets:
- Richer base-oil package. Würth carries five paraffinic fractions, one of them white mineral oil. Liqui Moly runs three, and at lower concentrations.
- Methyl methacrylate. Würth lists a trace, 0.1-1%, flagged as flammable and a skin sensitiser. It’s not in the LM 2640 sheet at all.
One caveat: Liqui Moly makes a wider range, including the stronger Oil-Schlamm-Spülung with 2-butoxyethanol for heavy sludge. Above, I’m comparing the standard products. Full breakdowns for every brand sit in our safety data sheets database.
How to use it, and an important warning
You use both the same way. Pour into warm oil right before an oil change, let the engine idle for 10-15 minutes with no load, then drain and swap the filter. One 400 ml can covers about 5 litres of oil.
Warning. Würth says the flush is not meant for motorcycles with a wet clutch, where the engine and clutch share one oil circuit. The solvent can change how the clutch grips. Liqui Moly sells a separate bike product, so on two-wheelers reach for that instead.
Which one to choose?
By the sheets, these two are close siblings from one group: both mild, both aliphatic, both carrying ZDDP. Würth adds more base-oil fractions and a trace of methyl methacrylate; Liqui Moly keeps it simpler and covers more of the range. Most of the time price and what’s on the shelf will decide it. If you want a different approach, a strong aromatic solvent base, look at our engine flush comparison and ranking.
Frequently asked questions
Are Würth and Liqui Moly the same flush?
Not identical, but close to twins. Both belong to the Würth Group and share the same C10-C13 base and the ZDDP additive. The extra base-oil fractions and the trace of methyl methacrylate are where they split.
Which flush is better - Würth or Liqui Moly?
On the sheets they’re very close. Würth adds more base-oil fractions and a trace of methyl methacrylate; Liqui Moly runs a simpler formula with more variants. Usually it comes down to price and what you can get.
Can I use this flush in a motorcycle?
Not if the bike has a wet clutch that shares the oil circuit; the maker advises against it. Buy a dedicated two-wheeler product instead.
Last updated: July 2026. Comparison based on Section 3 of the safety data sheets (SDS).
Sources: safety data sheet Würth Engine Flush & Cleaner (art. 5861310400, 2026), safety data sheet Liqui Moly Engine Flush 2640 (2021).
