My other thought is that some medications have short term memory problems as a side effect. Is your brother on any medications ? If her is, he could go to www.drugs.com , type in the name of the drug and see if memory issues are a side effect. Finally, is your brother having sleeping problems ?
For some vehicles, you're advised to change the coolant every 30,000 miles. For others, changing the coolant isn't even on the maintenance schedule. For example, Hyundai says the coolant (what many refer to as antifreeze) in most of its models should be replaced after the first 60,000 miles, then every 30,000 miles after that. The interval is every 30,000 miles on some Mercedes-Benz models, but on others it's 120,000 miles or 12 years.
How often to change your air filters can depend on the following: the type of air filter you are using; the overall indoor air quality; how many pets are in the home; the number of people occupying the home, and; the level of air pollution and construction around the home For basic 1-3 air filters, manufacturers usually direct you to change them every 30-60 days. If you suffer from light to moderate allergies, you could upgrade the air filter or change them [even more often|more frequently|every few weeks]3].