Cincinnati P-68, P-69, P-70: Which Hydraulic Oil Spec Is Which?

This mapping covers only the three Cincinnati Machine hydraulic oil specs P-68, P-69 and P-70 for machine tool hydraulics. Other Cincinnati P numbers cover other oils and grades, including gear lubricants (Lubes'N'Greases, 2019), and the machine's own manual, with its ISO and P equivalency chart, overrides any supplier table.

Which ISO viscosity grade is Cincinnati P-68, P-69 and P-70?

Cincinnati P-68 is ISO VG 32, P-70 is ISO VG 46 and P-69 is ISO VG 68, according to a Fives Cincinnati approval letter and the supplier data sheets that list the approvals by grade. The reference table below decides which grade a data sheet must show for each Cincinnati number.

The row that breaks the obvious order is P-70: it is the ISO VG 46 oil, not the heaviest of the three. The FS Industrial Hydraulic data sheet prints the pairing in one line, "Cincinnati Machine P-68 (ISO 32), P-69 (ISO 68), P-70 (ISO 46)" (GROWMARK, 2022), and a 2016 approval letter gives the same three pairs by product (Fives Cincinnati, 2016). A retailer listing for an ISO VG 68 anti-wear hydraulic oil names Cincinnati P-69 among its specifications, consistent with the table (Petroleum Service Company, 2026).

Is Cincinnati P-70 thicker or thinner than P-69?

Cincinnati P-70 is thinner than P-69: P-70 is an ISO VG 46 hydraulic oil and P-69 is ISO VG 68, so the higher spec number is the lower viscosity. The numbers are spec identifiers, not a viscosity scale.

ISO 3448:1992 classifies industrial lubricants by kinematic viscosity at 40 °C, and each grade spans plus or minus 10% around its midpoint (Anton Paar, citing ISO 3448:1992). ISO VG 46 runs from 41.4 to 50.6 mm2/s and ISO VG 68 from 61.2 to 74.8 mm2/s at 40 °C, so the two ranges do not overlap (Anton Paar, citing ISO 3448:1992). One supplier data sheet gives typical values of 46 cSt for its ISO 46 grade and 68.1 cSt for its ISO 68 grade at 40 °C (GROWMARK, 2022).

The order on paper runs P-68, P-69, P-70, while the order by viscosity runs P-68, P-70, P-69. Anyone who sorts by spec number, or assumes the last number is the heaviest oil, will put a VG 68 oil where the machine calls for VG 46. ISO 3448:1992 remains current; ISO last reviewed and confirmed it in 2023 (ISO, 2023).

How do you use the Cincinnati hydraulic oil spec table on a data sheet?

The Cincinnati hydraulic oil spec table is used on a data sheet by reading the product's ISO viscosity grade first, then checking that the Cincinnati number listed for that grade matches the table. A match on both counts is the minimum; an approval letter is the proof.

Work through four checks.

1. Find the ISO grade of the exact product supplied, not of the product family.

2. Find the Cincinnati numbers listed and which grade each one is attached to.

3. Compare with the table: VG 32 with P-68, VG 46 with P-70, VG 68 with P-69.

4. Note the wording: "approved" and "meets or exceeds" are different claims.

Step 2 is where family sheets fall short. Family data sheets often list approvals once for several grades. One sheet covering ISO 32, 46 and 68 lists only "Cincinnati Machine P-68" (GROWMARK, 2024), and a single-grade ISO 68 bulletin lists P-68, P-69 and P-70 together under "meets or exceeds" (Nulon, 2021). Neither line tells you which grade carries which number. In that case, ask the supplier which spec the supplied grade meets and on what evidence.

Where do you confirm a Cincinnati Machine hydraulic oil approval?

A Cincinnati Machine hydraulic oil approval is confirmed by the approval letter from the Fives Cincinnati laboratory, which names the product, the P spec, a lab reference and the Test Report Date. A data sheet line alone is a claim, not the approval.

A 2016 letter shows the format: it lists each product against its P spec and states, "These approvals are for a period of three years from the Test Report Date (TRD)" (Fives Cincinnati, 2016). The same letter requires the supplier to notify Fives of any reformulation and resubmit the product (Fives Cincinnati, 2016).

The laboratory then closed. Fives Machining Systems shut its lubricants lab in September 2018 and stopped approving products to the P specifications; Fives chief marketing officer Jason Melcher said the closure does not retire the P specifications but renders them static (Lubes'N'Greases, 2019). New products and reformulations cannot gain a P approval after that date, while products approved earlier may still be marketed against the specs (Lubes'N'Greases, 2019).

Because approvals ran three years and no new ones were issued after September 2018, any letter a supplier sends today will be past its stated term. Fives said previously approved products may still be marketed against the specs, so read the letter as proof that the formulation was approved, and ask the supplier to confirm in writing that the product has not been reformulated since the Test Report Date (Fives Cincinnati, 2016; Lubes'N'Greases, 2019).

For the machine itself, the manual is the reference. Fives pointed users to the ISO and P equivalency chart in the equipment manual for choosing a product as trade names change (Lubes'N'Greases, 2019).

What does a wrong Cincinnati grade on a data sheet mean for a submission?

A wrong Cincinnati grade on a data sheet means the submission contains a contradicting document, which is a different failure from a missing document. A missing approval can be supplied later; a data sheet that pairs P-70 with ISO VG 68 shows that the document itself is wrong.

Three outcomes follow. A buyer checking against the machine manual may reject the product line because the stated grade cannot meet the cited spec. A reviewer may question the other approvals on the same sheet. And the supplier must correct the source document, not only the cover letter, because the same sheet will go out again.

Before a tender or approval package leaves, compare each OEM spec named in the buyer's request with the grade on the data sheet and with an approval letter, and correct any mismatch at the source. Why compliant-looking packages still fail is covered in why a tender is rejected as non-compliant with every document attached. Lubinpla's submission document check compares the public spec with the product's approval label and judges a mismatch as a failure separate from a simple omission.