Replacement Filters, Belts, and Lubricants

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M25, 25XP & M35 Equivalent Brands

Caution: Use as a guide only (part numbers may be out-of-date, and what fits your engine my not fit others because of manufacturer or owner changes. Please feel free to update and correct)

Oil and Filters:

  • 10w40, Diesel Oil CF or CF-4 or CG-4 (do not use obsolete S, CD or CE)

(B-series engines use the same filters as M-25, etc.)

  • AC PF-57, X-88, PF-1127
  • Baldwin B179
  • CARQUEST 85452
  • Delco PF1127
  • Fleetguard LF3462
  • Fram PH-3593-A (replaces PH 2849A)
  • Kubota 70000-15241
  • Lee LF-2808
  • Motorcraft FL-799
  • NAPA 1064,1334, 21334
  • Purolator PER-4620
  • Purolater L14459
  • Universal 300309 or 209
  • Wix 51064

Oil Filters required for NEW Alternator Bracket on the M25 motor:

  • NAPA 1356
  • Car Quest 85356

There are a few other items to consider besides cost: Size -- if you have installed a high output alternator, the filter length might dictate that a shorter filter be used regardless of brand. It’s imperative that some space be maintained between the head of the filter and the alternator adjusting arm. The shortest filter is the KUBOTA. Other short filters are NAPA 1356, BOSH 72182, FRAM PH6607, however, these are also smaller in diameter meaning there is less filter element.

Clogged filter by pass: most (but NOT all) filters have a by-pass if the filter becomes clogged. The old saying, “dirty oil is better than no oil at all” is very true. This by-pass can usually be detected by seeing a spring on the inside of the filter which opens when the differential pressure reaches 11-14 pounds. You might also look at the filter and see a black rubber diaphragm under the small inlet holes. This is an anti drain back valve that keeps the oil from draining out of the filter when the engine is off (or when removing the filter).

Diesel Fuel Filters

(B-series engines use the same filters as M-25, etc.)
  • Fleetguard FF5226 (65% efficient @ 2u, 98.67% efficient @ 20u)
  • Fram P-7514, C6921 (82% efficient @10u, 97% efficient @ 20u)
  • Universal 298854 (98% @ 25u)
  • Kubota 15221-43170 (same as Universal.)

The following would not supply efficiency data (or I felt it was not worth finding it based on having the better options above.)

  • Purolator PER-262-F, F50262 (refused to supply efficiency data.)
  • Wix 33390 (rated 10u nominal i.e. 50% efficient @ 10u; Wix email: “We don’t supply beta [filter efficiency] ratios.”
  • NAPA 3390 (made by same as Wix)
  • AC TP807, TP1200
  • Big-A 538
  • Car Quest-86390, 86582
  • Hastings FF1119
  • Motorcraft FG72

Note that Racor spin-on cartridges (like R12S marketed as a 2u filter) are NOT rated 2u.
The R12S is 99% or better @ 4u (not 2u.)  Filter "rating" is a word game that manufacturers play. 
Per Racor - “From what I understand, the 2 micron branding on our filters is a leftover from pre NIST counting
standards (from before Wally started here in 1981) and is more of a marketing name than a designation based on
test data.” –Parker Hannifin, Racor Division 8/8/2012 email -

KWKloeber 2 Aug 2015


One of the very important things to know is the length of the belt. For M25 engines with the upgraded alternator bracket the length is 7400 or a tad shorter 7390 for Gates or Car Quest belts. The 7410 noted below may be a tad too long and the alternator bracket may bottom out and the alternator may hit the door. The "11A0000" series numbers MAY not provide you with enough information when buying belts, bring both #s with you to the store. Stu Dec. 2009

  • Dayco 15410
  • FLAG 41013
  • Gates 7410
  • Goodyear 13411

Belts for NEW alternator bracket on the M25 motor:

  • Car Quest XL 7390 / 11A0990 (Lee's Auto Supply), Inside ribs 25/64" x 39 5/8"
  • Dayco 15390 / 11A0990 (25/64") "Top Cog" outside ribs (for upgraded alt bracket kit)
  • Gates 3VX400 (1/2"?) (Inside ribs) (with alt kit)
  • Westerbeke 302190 / 7390 GATES XL 11A0990 (metric p/n)

Breather Intake Filter Components:

  • Universal #302181 (includes foam filter); #301049, Alum Honeycomb mesh
  • If you have the coffee-can type air intake, the honeycomb can be replaced with a stainless steel pot scrubbie (dollar store.)