by Robert Sanborn on Mon, Jun 18, 2007, who was a member of the STLE Society of Tribologists and Lubrication Engineers for 15 years.
The answer to that question is simply no.
No OEM can void a warranty due to use of a product. This is actually federal law the Magnuson/Moss Warranty Act. In this act it states that if a manufacturer requires the use of a certain product they must provide it free of charge as long as it’s on warranty. Unless a manufacturer has proof that an additive does not meet the specification of its product it cannot void the warranty. In terms of additives the cost for such testing to prove an additive is at fault is $1,500,000 for a diesel engine and about $500,000 for a gasoline engine. For this reason all of the manufacturers put out a statement through an industry legal opinion that states “the use of an additive will not, in and of itself, void your warranty.”
The reason this statement is made is that lets face it no manufacturer wants to test every single additive or product out there, thus they make a blanket statement that such use will not void their warranty; however, they reserve the right to test a product if they think it is causing damage. If they prove that the product does not meet their original specification then they could void the warranty with use of that product.
OEMs will not endorse or recommend an additive normally as they have engineered their product to perform based on a certain specification of lubricant. They would be opposed to anything that would lengthen the life of the equipment as this would hurt repeat sales and service that they depend on. If they have a specific problem with one of their pieces of equipment they will often recommend an additive to correct the problem.
In conclusion, you will not see an OEM say the use of an additive will void their warranty automatically as this is illegal; however, you may run into a dealer that thinks he can make such a statement as he is ignorant to the federal statue on warranty products.
Below are some excerpts from legal departments in response to oil additives voiding warranty:
"Detroit Diesel Corporation, as a matter of corporate policy, does not endorse the use of any engine oil additives for use in its engines. **The use of additional engine oil additives, in and of themselves, will not automatically void an engine warranty.** Rather it is our position that the use of additional engine oil additives **may** render the warranty voidable." - _Detroit Diesel Corporation, Bill C. Panagos Senior Patent Counsel_ "**I can advise you that the use additives will not, in and of itself, void warranty**. This does not imply, however, that failures which result from the use of such products will be covered under the Caterpillar warranty, which is limited to defects in Caterpillar's workmanship and materials." - _Caterpillar Inc. PJ Cain Legal Department_ "**Use of products we do not manufacture, sell or recommend with Mack vehicles does not, in and of itself, void Mack warranty coverage**. However, if the use of such products results in failure of a Mack component or adcersely affects operation of the vehicle, we would not accept the responsibility under the terms of our warranty." - _Mack Trucks Inc. G.W. Baily Warranty Policy Administration_