Technical Memorandum

Date: November 30, 2009

To: Melanie King, EPA OAQPS

From: Stephanie Meadows / Matt Todd, API

Cc: API RICE NESHAP Compression Ignition Management Practices Workgroup

Subject: Diesel RICE Management Practices and Oil Change Analysis Program

API appreciates you taking the time to discuss our submittal of information on November 2nd, including 

the MACT Floor Determination for 50 HP to 500 HP Diesel Engines (CI RICE). During the call, you 

requested additional information on industry maintenance practices for maintenance and our Oil Change

Analysis (OCA) programs. As the “best management practice”, API continues to support written

operating and maintenance (O&M) plans developed by the operator. This allows the operator flexibility 

to optimize the time interval between maintenance activities based on performance metrics unique to 

each company and engine application/service. Over the past decades, companies have developed 

maintenance procedures specific to each engine type and/or model to protect the substantial investment 

in RICE necessary to keep our operations in motion. API believes requiring these procedures to be in a 

written plan, along with the provisions of 40CFR63.6(e)(1)(i), will enable EPA to enforce the 

“management practice” for RICE without catalyst and ensure good combustion practices to minimize

the emissions of HAPs. 

API plans on providing additional information for spark ignition (SI) RICE in the coming months due to 

the six month delay to finalize regulations for these units. Since API had insufficient time to develop 

analogous information for compression ignition (CI, or diesel fueled) RICE, API would like to offer the 

supplemental comments on the fixed oil change frequency maintenance practice as proposed. 

Additionally, we are providing further clarification on an OCA program that would serve as an 

alternative compliance option for diesel engines. We believe both options fulfill EPA’s desire to have 

standards that are clearly defined and enforceable. 

Fixed Oil Change Frequency Management Practice

A. EPA proposed that oil must be changed in all engines <50 hp every 200 hours. API believes that 

this short of interval is unsupportable, burdensome and unnecessarily generates excess waste. The oil 

change frequency should be the same as larger engines of a similar category and no less than every 

500 operating hours.

B. EPA proposed that oil must be changed every 500 hours on emergency CI engines from 50 hp to 500 

hp. API believes that this frequency is appropriate for all emergency and limited use CI engines of 

any size.

C. EPA proposed that oil must be changed every 500 hours on non-emergency CI engines from 50 hp 

to 300 hp. API recommends an oil change frequency no less than 1440 hours.
D. API recommends that all oil change intervals specified in the final rule be expressed as ± 10% of the 

number of hours between oil changes. This gives operators some flexibility to schedule maintenance 

but, most importantly, the critical ability to finish any operating use of an engine during an 

emergency situation. 

Oil Change Analysis Program - Parameters

Many operators analyze the condition of the oil instead of assuming the oil needs to be changed or they 

use analyses to determine the normal oil change frequency. These OCA programs vary substantially 

based on type of engine, type of oil and the rigor desired by the company. A detailed laboratory OCA 

can test many different parameters, and oil change condemning limits of some of these parameters may 

be proprietary information of the lube oil manufacturer for competitive advantage reasons. However, 

many OCA programs have the following three basic parameters in common:

1. TBN

1

- Total Base Number (TBN) measures alkalinity of the lube oil. It is measured in milligrams 

of potassium hydroxide per gram (mg KOH/g). The higher the TBN, the more effective it is in 

suspending wear-causing contaminants and reducing the corrosive effects of acids over an extended 

period of time. Over time, the TBN can decrease from its original new oil value as it neutralizes 

acid build up.

2. Viscosity – Viscosity, a measure of flow, can change from new oil measurements and is a primary 

indicator of oil life degradation. In CI engines, contamination from soot can increase viscosity or oil 

contaminants, such as fuel oil, can decrease viscosity.

3. Water (% content by volume) - % water content (by volume) is the primary indicator of water 

contamination in the oil.

These three tests can be completed in the field using a field analysis kit available from several different 

vendors, or oil samples can be sent to a lube oil specialty lab for analysis. 

Specific warning levels used to indicate that the oil should be changed can vary by engine design, oil 

specifications and company experience. In the table below, the warning levels (also known as 

“condemning limits”) for TBN and viscosity are relative to the new oil specification. This provides 

greater flexibility to account for the differences in new oil properties. 

Diesel RICE Oil Warning Levels

Oil Parameter Warning Level Oil Degradation Indicated by 

Parameter

TBN (mg KOH/g) < 30% of new 

oil TBN

pH indicator

Vis @ 100o C, (cSt) -20%/+30% 

change from 

new oil

Oil viscosity 

Water (%) > 0.5 Water contaminant indicator

 

1 Note that TBN is used for diesel engines as the appropriate indicator for pH in OCA programs. SI engines typically use 

total acid number (TAN) as an indicator of pH in OCA programs. 
If an OCA is used, the operator would be required to change the oil within 14 days of receiving OCA 

results exceeding the warning level. Utilizing OCA programs have proven to reduce waste generation, 

while maintaining the operating integrity of the engine. 

Oil Change Analysis Program - Frequency

Initially, an OCA program should inspect oil at the same frequency as oil changes are required for the 

engine category and size (i.e., 1440 operating hours). However, after several oil test/change cycles have 

been completed for specific oil and engine type, OCA programs may allow extended periods before the 

oil is tested or changed. A regulatory precedent for this type of extended period is currently found in the

leak detection and repair regulations such as NSPS Subpart VV (40 C.F.R. §60.483-2a). Skip period oil 

testing/changing could prove effective in dealing with premium oils and engine designs that are capable 

of utilizing extended monitoring intervals. EPA should consider a form of skip or extended period 

monitoring that would allow for an affected facility to skip a required interval or extend the intervals 

based upon successful checks of the previous two intervals. For example, if a parameter warning level 

was not exceeded after two inspection periods, then inspection periods could be incrementally extended 

by 1,440 hours after the next oil change. If further testing/change cycles still indicate an even longer 

period is supportable, an additional skip period should be allowed. This would also reduce the amount 

of alternative monitoring requests submitted to the agency due to the use of premium oils and improved 

engine designs. 

API requests that operators have the option to change the oil within the specified frequency of the final 

rule or analyze the oil as part of an enforceable OCA program that contains, at a minimum, the three 

parameters above (for diesel engines). However, any final OCA rule language needs to also allow the 

flexibility for more comprehensive OCA programs to continue and also avoid jeopardizing proprietary 

information. 

Administrator Approved Alternative Programs

Because of the wide range of engine types, engine duties, and industries affected by this rule, the default 

“fixed frequency oil change” and OCA programs described above will not be suitable for all operators. 

The operator always has the alternative to apply for an alternative emission standard (i.e., work practice) 

under the provisions of 40CFR63.6620. However, API believes that EPA should provide streamlined 

procedures for approval of the alternative. For example, the operator should apply for the petition as 

required in 40CFR63.6620, but should be able to utilize the proposed alternative, unless the operator 

hears otherwise from the Administrator within 60 days.