Validated, approved, NOL or letter of support: what each document actually means
Four different pieces of paper get described as an OEM approval, and they carry very different weight. What each one certifies, what it does not, and how to read the reference number you are shown.
Every lubricant supplier says their oils are approved. Ask what by, and you get a document. The problem is that at least four distinct kinds of document circulate in this market, they mean substantially different things, and the word "approved" gets stretched across all of them.
This matters commercially, because a purchasing decision made on the strength of a misread document is a decision made on nothing. It matters technically, because the scope written into the document is usually narrower than the claim built on top of it.
The four documents, from strongest to weakest
| Document | What it certifies | What it does not |
|---|---|---|
| Validated listing | The engine builder has assessed the oil and published it in their own list of validated oils, naming the engine families covered. | Does not usually carry an expiry date, so the version number of the list is what tells you whether it is current. |
| No Objection Letter (NOL) | The OEM has reviewed field test results and states in writing that it does not object to the oil being used, within a defined scope and for a defined period. | Is not an endorsement of performance, and is bounded by the engine types and dates written on it. |
| Letter of Support | The OEM does not object to a field test being carried out on one of its engines. | Is not an approval at all. It is permission to start the process that may later produce an NOL. |
| OEM approval certificate | Common in automotive: the manufacturer certifies the oil against a numbered specification sheet and grants the right to make that claim. | Is tied to one specification number — a certificate against one sheet says nothing about another. |
The distinction that gets blurred most often is between a Letter of Support and a No Objection Letter. They look similar, come from the same department, and often name the same product. One says a test may begin. The other says the test was assessed and the result is acceptable. If a supplier shows you a letter of support and calls it an approval, that is not a subtle exaggeration.
How to read the scope, not the letterhead
Every one of these documents defines its own boundaries, and the boundaries are where the useful information sits. Four things to look for:
- Which engine families are named. A document covering two-stroke crosshead engines says nothing about your four-stroke auxiliaries.
- The exact product and grade. An NOL for a BN 70 cylinder oil does not extend to the BN 100 in the same product family.
- The issue and expiry dates. An NOL that has expired is a historical record, not a current position.
- The reference number. It is what lets you verify the document exists and is what the supplier says it is.
That last point is the practical test. A supplier who can give you a reference number is telling you something checkable. A supplier who can only give you a logo is not.
What this looks like in practice
For transparency, here is our own position stated the same way — including where the documents are weaker than a marketing page would imply.
| Product | Document | Reference | Status |
|---|---|---|---|
| SINOVA Marine CYN 50 BN 100 | Validated listing (WinGD) | Validated Engine Oils for WinGD Engines — Version 18, January 2026 | Current listing |
| SINOVA Marine SYS 30 BN 5 | No Objection Letter (Everllence) | NOL No. 17679-2026 | Issued 12 March 2026, valid to 12 March 2031 |
| SINOVA Marine CYN 50 BN 70 | No Objection Letter (Everllence) | NOL No. 25975-2026 | Issued 22 June 2026, valid to 23 June 2029 |
| SINOVA Marine CYN 50 BN 100 Group 1 | Letter of Support (Everllence) | Ref. 11012/2026 | Field test support — not an approval |
| SINOVA Marine CYN 50 BN 70 Cat 1 Group 1 | Letter of Support (Everllence) | Ref. 44527/2025 | Field test support — not an approval |
Two of those five are letters of support, and we label them as such rather than folding them into an approval count. The WinGD listing covers X, X-DF, X-DF-A, X-DF-M, RT-flex and RT-flex-DF engines, plus Wärtsilä RTA / RT-flex / X and Sulzer two-stroke engines — which is the scope written in the document, and the scope we claim.
A note on names
MAN Energy Solutions now trades as Everllence. Documents issued before and after the change carry different issuer names for the same organisation, which causes confusion when comparing a recent letter against an older one. It is a rename, not a change of position — but if you are cross-checking documents from different years, expect to see both.
The questions worth asking any supplier
- Which of the four document types is this, in the issuer's own words?
- What is the reference number, and may I have a copy of the document itself?
- Which engine families does the scope name, and does mine appear?
- Is it dated, and has it expired?
- Does it cover the exact grade being quoted, or a different grade in the same family?
None of these are awkward questions. A supplier holding real documents will answer all five without hesitation, because the answers are simply what is written on the paper.
Related
Need this confirmed for your engine?
Send us the engine make and model and the fuel you are burning. We will confirm the grade in writing, with the approval evidence attached.
Ask the technical desk