Opti-Lube XPD All-Season Diesel Fuel Additive (4 oz 8-Pack)

XPD is built around 2-EHN (2-ethylhexyl nitrate), the most independently studied cetane improver on the market. At 10.5-28% concentration, this is a high-dose 2-EHN formula (most consumer diesel additives run 5-15%), which accounts for the aggressive 1:64 treat ratio: one 4 oz bottle per 16 gallons. The brand states a 3-cetane-point improvement; no independent ASTM D613 test specific to this product has been published, but the 2-EHN chemistry class is well-supported in SAE literature and community feedback on idle smoothness and cold-start performance is broadly consistent with a real cetane effect.

Lubricity is addressed by soy methyl ester at a fixed 5%. FAME-class chemistry like this is the same base as biodiesel and is independently documented to improve HFRR wear-scar performance in ULSD. The brand claims over 45% lubricity enhancement; no published ASTM D6079 test for this specific product backs that figure, but 5% FAME is a meaningful lubricity addition regardless.

The detergent package uses a quaternary ammonium compound at low concentration (0.05-0.5%), which is capable of addressing carbonaceous injector deposits at the chemistry level, though at the lower end of typical detergent-package concentrations for a maintenance product. The anti-gel function is the weakest link: XPD is marketed as all-season with a -10°F cold-protection claim, but the wax-crystal modifier or other anti-gel active is not identified anywhere in the SDS. The cold-weather claim should be treated as brand-stated until independently verified.

The single-serve 4 oz bottle is a genuine convenience advantage: one bottle per fill-up, no measuring, no partial-bottle fumbling at the pump.

The right choice for owners of diesel trucks, farm equipment, or construction equipment running ULSD who want a named-2-EHN cetane treatment with confirmed lubricity chemistry and a proven track record in the Cummins, Power Stroke, and Duramax communities. The single-serve format makes consistent fill-up dosing practical for everyday use. Worth considering for anyone using non-Top-Tier diesel or experiencing rough idle or cold-start hesitation.

Skip it if the anti-gel function is the primary need. The chemistry behind that claim is undisclosed, so there is no objective basis to prefer XPD over a product with a named wax modifier and a documented CFPP improvement. Fleet operators who run modern CRDI engines and want documented injector deposit test data should note that the injector cleaning claim rests on community evidence rather than SAE test data.

The SDS classifies XPD as DANGER, driven by H304 (aspiration hazard, GHS08). That DANGER signal word, combined with H312, H319, H335, a confirmed Prop 65 listing, and a high-VOC aromatic carrier, places the health score at the bottom of the scale for this category: this is a full-strength aromatic-solvent concentrate, not a benign additive. The H304 classification means the primary hazard is lung aspiration if the product is swallowed or siphoned; aromatic petroleum concentrate entering the lungs can cause chemical pneumonia. Normal pour-use does not trigger that aspiration pathway, but the skin, eye, inhalation, and carcinogen exposures are all live during a concentrate pour. H312 (harmful in contact with skin) and H319 (serious eye irritation) are also classified in SDS §2; skin and eye protection are both warranted for concentrate handling. The aromatic carrier system, including 1,2,4-trimethylbenzene at up to 9.1%, drives the respiratory irritation (H335) classification and a recommended lungs tier for semi-enclosed or fleet-yard pour scenarios.

Prop 65 chemicals confirmed in SDS §15: naphthalene and cumene (carcinogens), plus reproductive-harm chemicals. The SDS §15 carries the explicit California Prop 65 warning statement. The concentrate VOC is estimated in the 350-450 g/L range from the aromatic carrier system.

On environment, the product scores at the category ceiling. Diesel treatment combusts in the tank; the exhaust pathway carries aromatic carrier byproducts. The concentrate itself carries aquatic toxicity from aromatic naphtha, xylene, and naphthalene if spilled; avoid concentrate contact with storm drains or waterways.