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Is it safe to switch to synthetic on a high mileage Volvo? 850 1996

posted by  someone claiming to be Hugh on  Wed May 20 08:13 CST 2020 [RELATED]

Hello All,

I have two 1996 Volvo 850 GLT Wagons: one has 420,000 miles and the other 350,00 miles. The one with 420,000 miles I purchased new, the other with 50,000 miles. I have consistently used conventional 10W-30 oil over the years. For reasons I can't understand, at this point in time is is cheaper to purchase a case of synthetic 5W-30 oil from Costco by 5 gallon containers than by the case of conventional oil. A concern that arises in my mind is: will the sudden switch to full synthetic risk blowing out the seals/gaskets on my two 850s and then I will be plagued with oil leaks?

I have in the past use synthetic oil in these cars for full oil changes, but only because conventional oil was not on hand or available in the moment without incident. Then I went back to conventional oil because it was cheaper. I change the oil and oil filer (Mann) every 5,000 miles.

I would welcome any advice or comments with regard to my concern. Thanks to all who reply.

Hugh








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    Is it safe to switch to synthetic on a high mileage Volvo? 850 1996

    posted by  KlausC on  Wed May 20 14:00 CST 2020
    Author: [PROFILE] [EVERY POST] [THREADS] [BEST POSTS] RSS Feed     [IGNORE ALL POSTS]
    last visit: Fri Oct 24 10:15 CST 2014
    [RELATED]

    Synthetic oils have better cleaners and break down slower than conventional oils. Engine seals get 'blown' out because of excess crankcase pressure.

    Now, the answer to your question. If the engine is very dirty and the seals are covered in sludge, introducing synthetic will remove the sludge - a good thing. If the sludge has been covering the seals for a very long time, the seals will have 'dried' out from lack of oil and removing the sludge will cause leaks - bad thing. BUT, as the seals start to swell with fresh oil, they will no longer leak.

    Pull the oil filler cap and take a look at the cam shafts. They are probably dark brown from oil baked on them. Synthetic oil will get rid of that dark brown color in about 2,000 miles. Your engine will be much happier.
    --
    Keeping it running is better than buying new








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      Is it safe to switch to synthetic on a high mileage Volvo? 850 1996

      posted by  someone claiming to be Hugh on  Wed May 20 20:24 CST 2020 [RELATED]

      Klaus,
      Thank you for your reply. I will “suffer” the use of full synthetic oil. My hope is, the inside of both engines are “sludge free” because of the regular oil changes over the years.

      Hugh






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