1998 Chevrolet Blazer Owner's Manual - Page 285

Automatic Transmission Fluid When to Check and Change Operating the engine withthe air cleaner off can cause you or others tobe burned. The air cleaner not only cleans air, it stops flameif the engine the backfires. If it isn't there,and theengine backfires, you could beburned. Don't drive with it off, and be careful working onthe engine with the air cleaner off. A good time to check your automatic transmission fluid level is when the engine oil ischanged. Change both the fluid and filter every 15,000 miles (25 000 k ) the vehicle is mainly driven under one m if or more of these conditions: 0 In heavy city traffic where the outside temperature regularly reaches 90°F (32"C) or higher. In hilly or mountainous terrain. When doing frequent trailer towing. Uses such as found in taxi, police or delivery service. 0 0 NOTICE: If the air cleaner is off, a backfire can cause a damaging engine fire. And, dirt can easily get into your engine, which will damage it. Always have the air cleaner in place when you're driving. If you do not use your vehicle under any of these conditions, change the fluid filter every and 50,000 miles (83 000 km). See "Scheduled Maintenance Services" in the Index. 6-15