Redex diesel dosing instructions inconsistent by bottle size

The Problem

The owner noticed that a 250ml Redex Diesel bottle is labelled as one dose, while a 500ml bottle is labelled as four doses, making the implied per-dose volume 250ml in one case and 125ml in the other. They wanted to know whether the two bottle sizes use a different strength formula to justify this difference, or whether the dosing instructions are simply inconsistent.

Solution

1. Check the arithmetic: if both bottle sizes are the same strength formula, a 500ml bottle should yield 2 doses to match the 250ml-per-dose rate of the smaller bottle, not 4.
   • A separate forum member also reported their own 250ml bottle states 2 doses, adding a further layer of inconsistency.
2. Contact Redex directly to ask whether the two bottle sizes contain different concentration formulas.
   • One member noted that Redex previously declined to answer technical questions on this topic when approached by qualified chemists on another forum, and had that thread removed, so a useful response is not guaranteed.
3. If no clear answer is available, treat the dosing instructions as unreliable and use the product at your own discretion.
   • Community consensus is that the labelling appears inconsistent and possibly marketing-driven, with no verified chemical evidence of efficacy available either way.
4. Buy when discounted if you use it for peace of mind rather than a proven technical benefit.
   • Members have found it for around £2.50 per bottle at Tesco or £4.49 for a twin pack.