Choosing the right engine oil can be a tedious process. How do you figure out exactly which oil will best protect your engine, and how long should you run that oil before it becomes detrimental to your engine’s health?
1. Read the owner's manual for a starting point
The owner's manual, and sometimes stickers or labels under the hood will provide a recommendation for engine oil requirements for the engine, including viscosity and any necessary certifications.
2. Purchase an oil meeting manufacturer's specifications
Whether it be Liqui Moly, Rowe, Pentosin, or any other brand, purchase the oil that meets the requirements of your manufacturer. Later on, as you receive oil analysis reports from the laboratory, you may deviate from the manufacturer suggestions. For example, BMW specifies a 5w-30/0w-30, but many use a 5w-40 with favorable results. Your individual experience with your cars will vary.
3. Run the engine oil for a few thousand miles
Usually I run the oil for around 3000 miles while driving carefully not to abuse the engine. No extended trips to the rev limiter and no aggressive starts. Remember to change your oil filter as well when you put in the new oil - keep the brand and model of oil filter consistent throughout the process.
4. Sample and change the engine oil
Using one of any engine oil analysis laboratories, have the engine oil analyzed for wear metals, additives, and contaminants. Tests are around $20 per sample, and many companies provide the service:
- Blackstone Labs - http://www.blackstone-labs.com/
- AMSOIL - http://www.amsoil.com/shop/by-product/other-products/oil-analysis-services/
- FRAM - http://www.framheavyduty.com/resources/fluid-analysis
- Wear Check - http://www.wearcheck.com/
Personally, I use Blackstone Labs and have been very happy with their service. The oil sample is packed into the sample container and shipped off to the laboratory for analysis. Analysis takes about a week and the results are available online through Blackstone's website.
5. Repeat steps 2-4 with different oils and compare the engine oil analysis
The engine oil analysis will contain a report of wear metals, additives, and contaminants. Wear metals such as iron, chromium, aluminum, copper, tin, and lead can indicate excessive engine or bearing wear. Presence of sodium can indicate an internal coolant leak, silicon can indicate a air intake filtering problem, and additive levels such as TBN can indicate how much longer the engine oil could have been run.
On my cars, I've been using the "Made in Germany" blend of Castrol 0w-40 (previously 0w-30) with oil analysis at every engine oil change. Oil analysis has indicated that the engine oil is a good match for all of my cars and can continue to provide protection for up to 8000 miles of service. This is an appropriate OCI (oil change interval) for my vehicle given the newfound information from the oil analysis.
Different engines will have different oil requirements - an engine oil that works well for a small-block Chevy may not work well in a Subaru flat-4, or in a German V8. Choosing an engine oil that performs well and is cost-effective is a process that takes a little bit of time and experimentation.
There are several resources that you can read to do more research on what oils others have used and determined to work well for a particular applications. Bobistheoilguy.com is an excellent resource community to read and ask questions about motor oils.
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