First-fill basics

Choosing a technical fluid is not a taste question. Somewhere in your service book — or on the reservoir cap itself — is a designation, and the whole job is matching it. Here is the short course.

1 · The handbook outranks everything

A viscosity grade like 5W-30 describes how an oil flows, not whether it is right for your engine. Two 5W-30s can carry entirely different approvals. Find the specification your handbook names first, then pick the can that answers it — that is the order of operations.

2 · Transmissions: match the designation exactly

Double-clutch gearboxes take an FFL-series fluid, and the FFL grades are deliberately not interchangeable — the friction feel of your shifts is calibrated around one chemistry. Classic automatics call a numbered ATF; ATF 134 for the Mercedes-Benz five- and seven-speeds is the canonical example. If the service book names a designation, that designation is the shopping list.

3 · Hydraulics: the cap usually names the can

European steering and central-hydraulic reservoirs are the easiest case — the cap frequently says CHF 11S in so many words. For level corrections, Pentofluid EHF is mixable with CHF 11S and CHF 202 as a top-off, so a slightly low reservoir does not demand a flush.

4 · Top off with what is already in there

An engine that uses a little oil between services should drink the same fluid it was serviced with. That is what the one-litre cans across this catalogue are for — keep your exact grade in the trunk and the gas-station mystery quart stays on its shelf.

5 · When in doubt

Cross-check the part number. Most Pentosin cans carry theirs prominently — our product pages list them — and your dealer's parts desk can confirm a designation from the VIN in about a minute. Write to contact@pentosinusa.com if a listing here seems to disagree with your handbook; the handbook wins, and we fix the listing.